+1 on Trojan Magnums.
I'd say try regular size condoms first. If they feel like they're too tight, then try upgrading to magnums. You may have condoms slip off just as much when they're too small as when they're too large... I used to have lots of problems with normal-sized condoms being too tight and coming off, whereas once I switched to magnum-sized (which are actually the same length as standard condoms, but have a larger width), that stopped happening.
Like Tyme2K, I tried Pleasure Plus (back before I switched onto magnums). I had friends that raved about them, but I was never really able to detect any difference in sensation. Might've been that I've been snipped but my friends still had their foreskins... hard to say.
Chase