My 3yo is pretty wide and has no withers yet. EVERY saddle rolls on him. What are some good pads and cinches to help minimize this?

5 star pads & classic equine featherlite neopreme cinch 

My new horse has mutton withers. I had to get a Lami-Cell roper girth. It has kind of a neoprene underside but it's absorbent and the roper shape helps to prevent it from moving. I also had to get a shorter girth than I expected. 

I love real wool liners - they have more grip than anything else that I can tell (aside from neoprene and tacky too which I wouldn't recommend).

Thinline pad liners are really good also, but I've purchased a few diamond wool liners and love them.  Real wool has a better grip than synthetic.

I don't use very thick pads - could never get them to work right even on a narrow horse. But I've got two wide ones, now, and on top of a recent purchase of a special made wide tree, I use those thin wool liners (Diamond wool are the ones I've bought).

Saddleright pad with a CE alpaca roper style cinch is what I use, I've had it on all body types and its never rolled 

I use a shimmed saddle pad on my wide backed no withered mares.  A CSI or "The Corrector" saddle pad works great on both.  One mare gets used to rope bulls (pick up horse) at the rodeos and the shimmed pads keep her saddle where its supposed to be.  I hate white withers and my 5 star was making hot spots on the mare in my profile picture (she is wearing the 5 star in this picture), switched to "the corrector" pad and no white spot and no rub marks. 

I'd vote a saddleright with a wool liner and a roper style cinch in felt.