Best gun in the game is MP34a with reload and clip mod. I can easily down 2-3 people at a time, even when it's 3v1. Gun is just too accurate and powerful. Even when people get the first shots on me I can down them. Highly recommend it. Even works at medium-long range.
I feel like it loses at mid-long range to the FAL and Mettler.
Also, I compared differences in TTK between the MP34a and AK and they aren't very different. The MP34a kills around 10% faster with bodyshots, but the AK kills 20% faster when you factor in headshots, as it only takes 4 to down at long range with headshots, but 5 with the MP34a.
I think a lot of peoples perceptions of the 'best weapon' are overstated. Most of the fully automatic rifles are quite similar in their TTK at close-mid ranges, close enough that it's likely to come down to the player rather than the weapon.
With that said there are obvious archetypes designed to dominate certain areas of the map, the FAL and Mettler dominant kind of midling, mid-long ranges, without much contest. A sniper can challenge but you're liable to die if you even miss one shot with the bolt-action. FAL burst can one-shot down with headshots too and if you're hit by any team shooting (as in, a burst from two players) the TTK is insanely low. AK's and MP34a's can also challenge but feature a much lower TTK across this mid-long range area.
The MP34a is proficient at close-mid, but if you want something to contest with longer ranged encounters then the AK is a better bet, you can burst fire headshots to down people much faster than you would with the HS39 XRC or MP34a. The XRC is a strickly close ranged weapon with a faster theoretical TTK up close than the MP34a but due to clip size it rarely pays off in my experience - only the best pick for single target blindfire, which leaves it with questionable overall efficacy.
Snipers obviously dominate long range and possess the fastest theoretical TTK in the game. In theory, a sniper can dominate at all ranges but in practice this is very difficult to achieve. Uncharted is not a game built for sniping, the variances in terrain elevation and player animations make headshots more difficult to achieve than in other shooters. Personally I would say the sniper is a bad pick overall, largely due to consistency. Dropping a shot with the bolt action means you've missed the team-shooting opportunity and your team are down on DPS output, unless you're landing every shot this will cause your team to lose team fights.
Let's say if it's 1 vs 2 and the sniper misses a shot, that functionally becomes 2 vs 1 for however long it took him to take that shot, and then however long it takes him to take the next - or switch to a sidearm where his DPS might be lower anyway. Against half decent players, you lose that gunfight. If a FAL user misses a burst it's much faster to compensate that, so the sniper inherently carries more risk, and that's my issue with it.
Obviously it's not without it's use though, I think having a single sniper per team can be useful in breaking up long-range stalemates where your team can apply pressure on a single down that other weapons wouldn't be able to achieve against more defensive teams, and there's some utility in dispatching sidekicks and things like that, but relatively situational and I wouldn't want more than one per team.
