I am considering taking the MCTS exam (employer will pay) with the intention of gaining a core understanding of the .NET framework. Also, I plan to take the C# version. What are the best preparation resources. (I am not interested in brain dumps, as my goal is to learn, not just pass)
In that case I'd suggest ignoring the MCTS exam for the moment - concentrate on finding the best resources for learning .NET and C#, whether those are books, training courses, or just allocating time to practising on non-employer code (where it's not expensive to make mistakes and take risks). If you know your stuff well enough, I'd hope that the MCTS exam itself would reflect that and not cause problems.
(Disclaimer: I haven't taken any MS certification exams myself, and almost certainly never will. I've never seen much point, personally.)
Get the Microsoft Press Self-Paced Training books on the exam you're taking. They each include a 15% off voucher towards exam cost. These were my only study aids and they covered exactly what was on the exams.
If you are just studying for the exam and already have a good understanding of C#/.Net Framework, I'd recommend the Exam Cram series -- I used them to study for the MCAD a few years back and they helped a lot. Using them you still learn quite a bit, but I wouldn't recommend them for a beginner. For a beginner, the Microsoft study guides are usually pretty good, they start from the beginning and explain a lot more.
Also, sign up for the second shot; It'll let you take the exam once to get an idea of where you're weak/what the tests are like (or you could just pass it the first time). Second Shot
I highly recommend the self-paced training books and also look over the requirements as listed on the Microsoft Learning website for the individual certifications, these requirements provide great entry points to start reviewing MSDN documentation on the topics as well.
If true understanding of the topics is desired, I would additionally recommend that you start practicing some of the items that you start learning about, create sample applications and truly get to know the content.
I have been in to doing certifications till last month, but now I am thinking to start doing some just to do some learning. I think the Test series by MS is the best place to start and then you can use some sites to do tests to prepare more.
Now you have option to take the 2nd shot free utilize it:)
First check the Errata list of the self paced training kit of 70-536: http://support.microsoft.com/kb/923018/en-us
It comes in 4 parts. I can't imagine this is the best resource around.
You should use some short of practice tests. See "has anyone get experience of both measureup and transcender practice tests" for a review of some of the practice tests on offer.