Hi and welcome, for my part, the most important are the TRIM, TMS, CMS(at least to release), weapons release and triggers of course, Speedbrakes, Master mode and CHINA. What's the model?
Anyway, you will quickly realize what is your need or not, also don't forget to add a modifier, I've a switch for my hat which allows me to use it to slew and lock the designator and Trim the aircraft...