Honestly I would say currently its Dark Angels, when you have a banner that allows you go go ape shit with bolters, squadrons of land speeders nearly twice the potential size as other chapters, bikers and terminators as troops, and even 5 man tactical squads that can rock out heavy weapons, its kind of hard to compare.
But my preference is still space wolves. Devistator squads with 5 rocket launchers, a librarian with d6 autocannon shots or 3d6 lasgun hits to a unit that slows them down isnt to shabby. Giving their tacticals a walking cyclone missile launcher just adds to it. Wolves are cheaper bodies and have a better melee defense built in than most other chapters, so you can afford to spend more on guns.