I'll narrow it down even more for you. Aside of the things Trainer said i'll point some other stuff out:
1) SR-3M needs no mods to perform what it does, SR-2M is pretty bad without them, however nothing is more scary than running into a SR-2M with full ROF mods ( 20-ammo setup ). Would even make a para user say "WTF". Up-close it just SHREDS everything.
2) Rifles... Well i'll say it like this:
m4a1 mk3 and XM8 are very similar in their behavior.
Sako is something that has a recoil, is tricky to use/kill with, but up close can yet again be a problem for the enemy.
famas mk3 is 1 of a kind out of the list... it is BEAST up close ( also probably beats the all-known para ) is decent on medium range... however is REALLY bad at longer ranges... Basically treat this like a pointman weapon. The biggest con this gun has, is if you equip it.. you basically have 2 "pointman" classes to choose from, and no rifle...
3) Saiga-12 just sucks.. in everything... it's unnecessarily hard to use... it almost never 1-shot kills, it has slow rate of fire... just plain-around BAD shotgun imho.
So yea Striker-12 by far out of these 2.
4) hmmm ASW or TPG... 1 thing I can say is that ASW requires some knowledge to use well. You also need to be able to quickswitch ( preferably ) otherwise it's just REALLY slow. TPG is the more "classic" weapon, when you shoot it... you know your shooting something that kills, the sound can be very satisfying... the "BOOOOM" of the TPG just overall sounds better than the " Pssst " of the ASW...
Other than that, TPG has a few "longer-phased" scopes, ASW however has quicker zooming ones... ASW is really long, so people will sometimes see you coming from around the corner and pre-fire you.
Dunno why trainer here dislikes TPG so much to say that ASW outclasses it by far.. sure it's better but not by a great deal. As I said ... ASW is LONG, not so satisfying and you MUST quickswitch ALWAYS with it, those are the first cons that come into mind.