I used to play paintball, but I've moved onto airsoft. I can understand why people play/like/enjoy them, but I vastly prefer airsoft.
Part of the reason was the community. Whilst it's true there's always bastards in a community - round my neck of the woods the paintballers I met were all twats. 2 types - the annoying young kids with too much money (or should that be parent's money?), who think it's cool to shout homophobic/racial/whatever abuse over an Xbox mic and do so whilst playing paintball - or the elder player, really arrogant, bought all the gear, thinks he owns the place (and does so by slyly wiping paint off himself...) Gets defencive about his gear - he brags about it, but if you ask him about it, he goes nuts.
I can't stress this enough, I'm not saying all paintballers are like that, just the ones I met.
I'm certainly not saying airsoft is full of saints. I've met some real wankers playing, both similar to the above paintballers I've mentioned - but on the whole, the guys and gals I've met are very nice, friendly people.
Secondly, cost. Whilst it's true some replicas may cost more than a marker - ammo wise (and batteries/gas) it's far cheaper. So far this year I've gone through 37K rounds (I'm a support gunner). It's cost me £39. If that was paintball ammo, I'd be looking into double figures for 3 thousand rounds.
What else do I like? Well, the play style. We can do generic Sunday Skirmishes. Relaxed, hi-caps galore, friendly. We can do MilSim. We can do HistoricalSim (I've done a pretty good Nam game) We can do FilmSim - act like every action movie character, fire from the hip, shouting Arnie quotes and not taking it seriously. So much diversity. Marshals put effort into the game, making it more than "capture the flag" or "team deathmatch".
The gear. Unless you're part of a team, very few players ever look alike. The same goes for replicas - I've never seen, in 3 years of skirmishing, another player with an L86LSW. Everyone is unique. It makes things interesting, and people become recognisable ("he's that guy who wears the USN blue camo stuff!" or "hey, it's that nice guy who dresses like a 60's USSR paratrooper" etc). Of course, there are the dreaded 'geardos' and 'stitch-counters' but they're (luckily) few and far between.
I've had the "why don't ya join the army" line - but there's some good reasons why I don't. Firstly, I'm doing this for enjoyment. Like I also do cooking, painting or photography - you've never asked why I don't make those my job, and I find it fun. Secondly, it's good exercise - running about, with all that gear for a day (or 2) in the great outdoors, far better for me than sitting infront of an Xbox. And finally - I'm just not fit enough by Army/Navy/RAF standards - asthma and with a heart defect. Its a case of "I would if I could".