Its all your style. I personally love the sniper rifle. Intervention is my game because anything else is too easy
There are two types of sniper classes: the silent and the one shot one kill. I used the silent before I prestiged, and then I used one shot, one kill after. I averaged about the same, except I got more kills with 1 shot 1 kill but fewer kill streaks. Makes sense.
1 shot, one kill: (Bling*, stopping power, Steady aim**)
silent: (bling*, cold blooded, ninja)
get all of those pro asap because sometimes the secondaries are better than the primaries (steady aim pro lets you hold your breath much longer)
* bling is not a must-have, I use it for thermal and silent or any combination of sniper. I use more than one because i can't use thermal on a snowy region, or a silent weapon isn't powerful enough.
** you dont need steady aim, but I like using it for two reasons:
1) I use akimbo silenced machine G18 pistols. better than shotguns because its almost as powerful, longer range, and silenced.
2) holding my breath for long periods of time. I need it when facing off against another sniper. He may think he is barely sticking out by moving slowly, but i have a bead on him. Being able to hold you breath longer is easier for waiting for a camper to run up to his spot, or for someone slowly moving out to aim at you.
sub machine guns are my second favorite. I use them alot. UMP ftw! try it sometime, its great, 3 shot kill with it silenced.
I used to use an M16, but it has some downsides with its burst fire. If you miss, you can be skrewed. But its still pretty good. I like the ACR or SCAR.
And for LMGs I used the RPD, but I'd rather use an HBAR. The RPD is way too inaccurate and using "grip" is a waste of an attachment. So use something else if you can. However, I use the RPD class for one reason: Hardcore SD. I use it as my explosives class. I team mine up with RPD, Javelin (best wep ever for SD) Scavenger, Danger Close (DANGER Close Pro is deadly: extra damage from air support) and Sit Rep. Sit rep is useful for more than just finding C4 and Claymore. It also shows where they are camping. Its a fun class to mess around with, try it sometime if you can!
Happy slaughter~!