I've got a Xikar, which seems to work well. A friend of mine seems to like his Credo better than the Xikars he had though.
Unless it's a torpedo, bellicoso, or a really pointy perfecto another good way of cutting a cigar is with a small pocket knife. Just cut a circle through the cap. Mostly I'm lazy & just use the Xikar, but if it's a really high end stick (Opus X, Silvio, etc.) or over 52-54 ring gauge I'll use my mini Swiss Army knife. I don't think I've ever ruined a cap with a knife, so I'd say it's probably easier than pinching & offers similar control. As an added bonus, you don't need fingernails. Using a pocket knife on a torpedo is asking for trouble though.