I think it's going to be pretty unique for each rider, I rode 15 wide all summer and tried 18 wide once and wasn't feeling it, just made a new set up 2 weeks ago with 20 wide and for some reason fell in love with the width the first time riding that wide
I personally think barspins/turndowns look much better with wide bars, I didn't notice any change in bri difficulty, if anything it became easier for me, not that they are a trick of choice for myself
if you feel like you want/are ready for wider bars go for it, just don't do it because you hear that everyone else is or if someone is pressuring you to