The best? I'd say Dillon or Thumler's Ultra-vibe. Have a Lyman 3200 Autoflo now, its nice but its nowhere near as aggressive as those two. The Dillon is loud, but the Thumler's is very quiet. They've tuned that thing just right.
Had the Autoflo 2200 as well, in addition to the small Dillon. The Autoflo feature is not as fast and doesn't work nearly as well as a Dillon or RCBS separator for getting the media out of the cases.
Most generic firearm company tumblers are cheap Chinese junk. If you want to go that route, save the money and just get one form an auto supply shop. Same crap for half the price.