Floyd Rose trems. I have no use for the device, too intricate, too delicate. And Bigsbys, not all but the Bigsbys that incorporate the down tension bar. That little bar removes a vast percentage of the response that you are looking for in a bigsby. That and their clunky look, and manufacturers that mount the wrong Bigsby on the wrong guitar and think we don't notice. The B-5 or B-50 should never be on an archtop or any guitar that has a semi German Carve. The Bigsby is flat, the guitar top is not.....
I do like guitars with trems, Fenders being my favorite, but when you pick up something like a PRS with no trem, it forces you to bring all your technique and tricks to the fore cause you don't have that little sonic crutch.