Personally i would go with the sniper only because i think its more FUN, hiding in the bushes or just hiding anywhere lol.

I would say the M4 but thats because I am more of a assault kind of guy but if you like sniping I would get the sniper.

I don't know a whole lot about Airsoft, but I'd imagine it would be based on your type of play style. If you like running around and having something full automatic, then the M4 would be for you. If you like precision and waiting for your targets then long barreled rifle is for you(I don't like calling long barreled rifles "Snipers" as it throws me off)

It depends on what you like doing while using airsoft weapons, for instance

Sniper: i would choose the sniper if you are more into target shooting from medium-far distances and enjoy a time where you build accuracy skills by practicing with the sniper rifle, if this is you then i would choose the rifle.

M4: i would choose the M4 if you are into a shorter distanced multiple target kind of time using airsoft weapons, you could also build accuracy with this but to most people i know it is fun using the M4 if you are into a timed shooting kind of thing.

Get the M4! They are fun as hell to use

If you're using a sniper you don't tend to get too many shots off, people move much faster and if it's a bolt action sniper you've got a problem if you miss the first shot, now, this is assuming the sniper doesn't have a full auto switch, but I'd go for the M4

I would definitely get the sniper. But I wouldn't be able to anyway because I'm not 18