Best modern day jet fighter simulator?

Hey, i'm taking suggestions to a nice modern day jet fighter simulator, that i would like to purchase, i have read some of you have a interest in this subject and i'm wonder what you think a good modern day jet fighter simulator game is.
thank you in advance.

well, lock on: modern combat is pretty good, but you need a top line computer if you want all the nice effects and textures. it has both US and Russian made fighters.