Check out
www.mtbr.com
Also, mainstream brands such as Shimano, Avid, Rock Shox, etc are all generally good products and will serve you well.
I may help us out a bit if you let us know what parts you are looking at specifically, or is this just a general question? A general question can only really be answered with a general answer though....... (see above)
My advice is to upgrade bits at a time, not only so that you don't burn all your cash, but also so that you can more effectively learn the differences or benefits of the upgrade after it has been done ,and appreciate the improvements.. rather than dumping a whole bunch of money into lots of parts all at once.