It really depends on when you go but these are the ones that work best for us.
MK - All the "Mountains". Most times you can get a FP, wait in line to ride and then by the time you're done, your FP is ready!
AK - Everest, Everest and then Everest. Possibly the Safaris if you don't go first thing in the morning (which I reccommend).
HS - R-N-R Coaster, Tower, Little Mermaid (if you have small children)
EP - Test track, Mission Space (if you're up to it), Soarin'
Again, it depends when you go but we find that using your FP correctly is an absolute must if you plan to ride all the good rides. If you're waiting in line for more than 30 minutes (except in peak times) you are NOT using the system correctly.
Good Luck!