Well, I have gone through the first semester and used several books, so I have recommendations for you if you are spoilt by choices. (No, I don't buy all books, I borrow some from the libraries)
I'm using more books for second semester, so by the end of this semester I'll recommend some books for the second term.
But sadly I can only recommend science subjects..anyway, here goes (Updated 24/11/2014 - refer to texts in italics)
If you want the best notes ---> Longman (by Goay TC, Wong YH and Suraini Basir). Pelangi is good as well but not as good as Longman.
If you want many exercise --->; Pelangi (by Wang HK, Goh XH and Mohammed bin Hashim). There are plenty of objective questions and subjective questions in it. Longman and Oxford contain plenty of exercise too but not as many as Pelangi.
Personally I would prefer Pelangi over Oxford and Longman, because the notes are not too lengthy and there are enough exercise for you to complete for the examination.
So I would recommend Pelangi.
*It is widely believed that the one published by Ilmu Bakti is the best because one of the authors work in MPM, or so they say. I personally do not think that makes the book better. Anyway, Pelangi is already good enough.
Do note that Pengajian Am is about contemporary issues, so when you go for bookstores please look for the newest edition. An old edition, even if it's one year old, is quite 'old' for PA. A lot of things and changes could happen in a year, so go for the newest one possible.
Before you select your choice, you should realise that both Oxford and Pelangi Physics are published by the same author - Poh LY. Therefore, it would be unnecessary to buy both especially since the notes do not vary much and the exercises are mostly similar.
Well, I didn't use Longman for reference, but I did the exercise in it. If you're taking Physics, do remember these two authors - Lam CS and Lim SK. Their books are of very high quality and the questions are very very challenging. Therefore, if you want to try challenging questions, go for Longman. If you can solve all the questions without difficulties, you're ready for STPM!
The notes for Longman appear to be sadly vague and insufficient. It gives you enough for answering exam questions but it doesn't provide thorough concepts.
Pelangi and Oxford have decent notes and scant examples. The notes are short and lack detailed explanation, but if you're hardworking and willing to twist your mind, the notes should be enough for you as you can interpret them yourself.
Since both are published by the same author, and since I've used both, I can tell you that the notes are mostly similar. Oxford lacks exercise. Pelangi has more but the problem with Pelangi is that the answers given are not complete. Some only show the final answers but never show the steps, so if you do not know how to solve a question, you're doomed. Whereas for Oxford all answers are given detailed explanation. Both books contain quite a lot of overlapping questions so please, save your money and don't buy both.
So Personally, I would highly recommend Longman. It might be better if you go for Pelangi for the notes, and then Longman for the exercise. I would strongly discourage you to try Pelangi's exercise on first try, you'll get extremely shocked especially since this is the first time you're exposed to STPM level Physics. Go for Oxford exercise first if possible, if not go for Longman. Pelangi might be too overwhelming on first attempt.
For the first semester of Chemistry, you'll need a very good book because Physical Chemistry can be very abstract and the past year questions (or actual STPM questions) are quite tough.
Oxford, published by Tan YT, Loh WL, Lim MH and Ho SC probably has the best notes. The notes in it are very good and detailed but, like all Oxford books, it lacks exercise.
Longman is a bit unnecessarily long but very,very detailed, and both Longman and Pelangi contain a lot of exercise for you to do.
Personally I would recommend Longman. Oxford isn't a bad choice either. If you really can't decide which to buy - go for Longman.
*If you want the best notes, go for Pelangi Chemistry for the terminal system published by Loh YL and N. S . The notes are very very long but very detailed and the explanations are very good. Pelangi has terminated publications for the terminal systems, and the new books by Pelangi for Chemistry are written by different author: Peter Yip. So try searching for the books in libraries, highly recommended.
Be proud to for taking STPM Chemistry. I have not found a single pre-university programme that includes Phase Equilibria, one of the craziest topic you'll encounter, as part of its syllabus.
You're lucky you're not the first batch. Maths T has the most changes after they changed the syllabus and many of them are transferred from the old Further Maths.T. Because the new topics are tough and plenty, all books are published in a haste and there are either low quality notes or out of syllabus topics in all the books. And ergo, we, as the first batch, suffered from learning the wrong things and had no reliable reference.
Anyway, if you want good notes, go for Pelangi or Longman. They give quite detailed explanations but some of them are unnecessarily long-winded. Still, it's better than nothing. Oxford contains very vague explanation, a lot of the examples are wrong, and there are many out of syllabus topics like locus of complex numbers and distances between vectors.
If you want exceedingly challenging exercise, undoubtedly Oxford is the best. Some of the Oxford's exercise is beyond STPM standard and on par with university level. But do note that Pelangi and Longman too have great exercise. They are tough too, but not as tough as Oxford's. If you can complete Oxford's exercise, you should be ready for STPM. But personally I think Pelangi and Longman would be suffice if you think your Mathematics isn't very strong.
But there are a few problems: Oxford, like I have mentioned, contains too many out of syllabus topics like Gauss-Jordan Elimination Method (whereas Gaussian Elimination, which is in the syllabus, is not included), Locus in Argand Diagram, and Distances between vectors. Pelangi contains misleading notes such as wrongly teach Gauss-Jordan as Gaussian. Longman does not give answers for curve sketching.
Personally, because all three books are bad in some ways, to compensate them, I used both Pelangi and Oxford. But if I were to choose only one in the three, I'll go for Oxford for the exercise.
*Oxford has updated the first term book. Now with much more appetising front page and the topics which aren't in the syllabus have been removed, and Gaussian Elimination has been added in. So if you were to buy this book, find the version which has "Algebra and Geometry" and a huge "updated version" printed on the front page.
The new version has fixed all the problems previously are found abundant in the first version. Out of syllabus topics are removed, and those that are in the syllabus have been included, although on first glance I would say they're included in quite a haste and resulted in a rather hazy explanation that is likely to not contribute much. Anyway it's better than having no guidelines at all.
It is said to have been reviewed by an MPM officer, so I guess it should be the most reliable book. The exercise is tough as well, and much harder than university level Mathematics (well, at least the book 'University Calculus', for the topic of Vector and Functions). Do appreciate the book.
Longman has some problems. I realised it omitted trigonometry in its chapter review exercise, and there are only a very little exercise on trigonometry. Trigonometry is very important as you'll still use it for second term, and would be extremely helpful to solve lots of calculus related problems. Since Oxford has fixed most of the book's problem, I will now strongly encourage Oxford Fajar.
MUET stands for Malaysian University English Test, and it is mandatory for you to sit for it if you study form 6. Contrary to what most people believe, MUET is not an easy exam, unless you speak English as a first language, are extremely functional in the language, and have been using it for your whole life. Even if you have one of the above, you're still likely to face difficulties scoring it.
MUET is a completely different exam from SPM/1119. There are four components in MUET: listening, speaking, reading and writing, and most of my friends, including me, found writing's the most challenging. There are two tasks to be completed, and the marking scheme oddly requires an extremely profound maturity most 18/19 years old have not attained and your language must be strong enough to relate the information given and elaborate on your points maturely and convincingly. Writing it like how you wrote for SPM is going to give you marks on points, but not task fulfilment.
Listening and speaking require repetitive training, while reading requires lots of exercise. Because MUET is a language test, there's no best reference books because it depends on your proficiency in the language. Contrary to the other subjects, this exam requires some alive and huge twisting and it allows your imaginations to run wild. So, make sure you have grasped basic grammar. Avoid tossing bombastic words because bombastic words are mostly too flowery for a factual essay, and frankly bombastic words do not impress your readers.
If you need at least a reference book, I'll say you go for past year papers. The reading part is really tough because the passages are taken from articles mostly meant for first speakers, the points are pretty vague and catchy, and the answers are very close to each other and a high analytical skill is required if you wanna score the paper.
My personal experience tells me that none of the reference books out there published reading exercise that are on par with the actual exam. The book published by Wayne WH is way too easy so save your money. Go buy past year papers. That's my only advice.
If you're curious what band I got: I got a band 5, merely grazed the border by scoring 220.
*All reviews above are solely my opinions.