BlameItOnGod13 
So just in case people are starting to play BF4 or just aren't quite sure which gun is the best for each class I would like to take the opportunity to share my finding's thus far.
first off, stability is now your accuracy. i know this seems ass backwards but set-up a gun with high stability and take notice how much more accurate you are at range. keep this in mind when choosing and personalizing your primary weapon.
Assault - LevelCap recently released a video that confirmed many people's suspicions. the ACE 23 is the BEST ALL AROUND assault rifle. the M416 is a very close second. the AUG A3 is VERY accurate but you sacrifice on rate of fire and in "OH FUCK" moments.
the AEK is also a very good choice if you can control the recoil and tap fire. it is SUPERB is close quarters and has a pretty fast reload. make sure you put an angled or folding grip on it to control that first shot recoil. the Famas is also a viable option, but again you will need an angled grip or folding grip.
the SCAR-H shits on everyone in TDM or DOM provided it doesn't turn into a CQB.
Engineer - my personal favorite has become the AK5C. very good all around gun especially at range which is something you need to take into consideration for Conquest. the AK12U is also a solid option. however when I want to drop bums fast you can't go wrong with ACE 52. stay away from PDW's in conquest. a case could be made for the MX4 or UMP45 but all previously mentioned carbines are superior in my opinion.
Support - my favorite has always been the RPK12 however I have really been enjoying the MG4. when you feel the need to dish out huge damage while being fairly accurate the PKP is the best choice provided you tap fire constantly at range. it's almost like the M60 was in BFBC2.
Recon - i don't play that class much but when i do i play aggressive and use carbines. the DMR damage model is pure shit. there is no upside to them currently. for Rifles talk to Raz.
as far as secondary weapons go there are plenty of viable options. my personal favorite is the Compact 45. similar damage model to the 1911 but with 4 more rounds in a clip. the G18 destroys at close range but struggles everywhere else. 93R is pretty nice all around. the currently delay between shots on the MP412 Rex and 44 Magnum have effective made them fairly unusable for try hards like me. hopefully that changes.
as far as attachments go, for Conquest or Rush i like to set my gun up for stability. i find the laser sight is good way to go. the tactical night is now more viable because it only turns on when you ADS. if i'm playing pure infantry games i always use a silencer so i can stay off the mini map and be a sneaky bastard. my favorite and most viable sight, in my opinion is the Kobra RDS. i find that when shooting snipers of buildings or looking into bright areas you lose the dot on Coyote and Reflex. Potato or Stubby grip unless your using a gun with horrid first shot recoil.
i almost always use Heavy Barrel on my pistols.
hope that help's some people stuck on which guns to use for which situations.
