If you've got arms like a gorilla then go for an M60. If you're a more normal build then the M249 will suit better. I've tried to carry a team mate's M60 and it's quite a weight to lug around all day and really needs to be fired prone or resting on something. The M249 ain't no lightweight either, but you can shoulder fire it if need be.
As for range, ammo, accuracy, etc., they're both airsoft guns, so there's really no difference apart from the size and weight and that the M249's can use an M4 mag as well as a box mag, whereas the M60 is box mag only. The other thing to look at is type. The M249 standard version with the fixed stock will take a larger battery than one with the para stock.