Did a search and didn't see a topic on this.
Bushwhack isn't a feat I'd be comfortable picking up normally, but if you're about to get the drop on your target, it can be a powerful pickup. Combines well with Chokehold and Kobold Style.
What feats do you keep in mind for Flexibility picks?
I really like monkey style.
It can shut down some enemys and it can make your society gm look at you with the most miniacle grin when you start break dance fighting those Rangers shooting your party.
I really like Equipment Trick- Rope for a lot of situational goodies.
Equipment Trick seems to be a good one to know the abilities of, since you can pick it up as you need it (and the prereqs for those tricks).