The soul rip is cheap as hell, and he's actually used it very few times. I rarely include it in my thought process when thinking about Adam.
Honestly, maybe Alan. I'm a huge fan of both these guys, and it would be a monumentally sweet fight between two savvy veterans.
Alan simply has more raw energy output and options with his ring/power (depending on the incarnation). So the fight would be his to lose. But Adam's not far behind him in power, and would be tough to take out since he wouldn't try to go toe-to-toe with Alan.
I'd give Alan the slight majority simply because I could see him resisting a soul rip, as well as Warlock's telepathic attacks, and foiling (or at least not succumbing to) his trickery.