There are basically three options with psionics.
1.
Expanded Psionic Handbook: This is a "Spell" based psionic system, which is both good and bad. Bad for flavor, but good that it uses a familar system, but make just enought changes to make it different. The changes from 3rd to 3.5E were very good and badly needed. The only real complaint I have for the XPH is the lack of psionic support from WotC.
2.
The Psychic's Handbook: This is a "Skill" based psionic system, which is very different from magic spells. The one problem with this system is that power wise, the Psion has a very big edge. I have found the Psychic's Handbook works best in a low psionic/low magic setting, like most of the D20 Modern settings. Your PC psychics will also spend all of their skill points on their powers, so they won't have many social skills.
3.
Psionics Ascendant: This is a "Feat" based psionic system, which is probably the closest in nature to the original psionics rules in the original D&D Player's Handbook. I have been playing around with this one for the last few months and while I would still prefer the XPH, there is a lot of stuff here to hijack. I have a review in the works for this one I will try to get posted soon.
Since the XPH is the "Official" handbook, it will get the most support, but aside from the Mind's Eye (see link above), that isn't much. Eberron is promising us psionic support, but we have yet to see if WotC will actually allow this to happen.