Well Arc is one of the top companies, Jl is very good because it has a regulated power rails, so you get that 100 watts from 4 to 1.5 ohms, Xtant is supposed to be nice also. So i guess it depends on you budget and your subs
Personally, I'd take the Arc, then JL, then Xtant, but that's just my preference. All are fantastic amplifiers, you should choose on SQ, price, and also features offered. The Arcs are extremely well built and have tons of SQ and headroom, they are also designed by Robert Zeff, who IMO is the best amplifier designer in the industry.
jonathan.... do you kno the max watts rms and peak of those amps? (arc,jl xtant) i was thinking about pushing jl 13w7 or RE x.x.x so i need some serious power... thanks for ur info