Most of the guys I play with run M4/16 platform guns.
Other popular ones are AK and it's variants.
These have a plethora of internal and external upgrades and everyone and their dog has one so it's not that expensive to get fixed/replacement parts.
The other ones it might be harder to find mags and accessories for however the G36 I believe uses a V3 gearbox (same as AK) so the internals and upgrades will be the exact same.
As for the SCAR I haven't seen many however it's relatively newer and usually more expensive for good quality ones (like VFC). I would like one but the thing is I wouldn't want to drop $800 for one (keep in mind that I'm a student here so $200 is a lot).
ಠ_ಠLess QQ more Pew Pew
READY TO >> RACE