What is the best weapon for all level?

Personally, I like using the AG-94 for the majority of the time. It works best for me but some missions are best for a sniper. I use the M82A1A with a high scope for Wake of the Fallen mission. You should always use silent weapons for missions that require you to be undetected though too so don't just use the same gun for every mission!

I just use the gun it gives me because the game picks the best gun for each level and I'm 100%complete with the game

AK 47 IS NICE FOR ALL MISSION

Personally I like to use the M16A2 for assault missions, and the SR-25 for stealth missions it seems to be the best sniper rifle.

Personally, for me, use any gun (for stealth missions) that can have a surpressor added to it, and for assault missions, use the MK.48 or the HK36 later in. And for pistols, go with the 226, and then steal a bady guy's F57, the one with 20 bullets per round that almost every bad guy carries, it does the same as a 226, but it hold more ammo. I'm still stuck in In The Balance or whatever it's called, where you defend the CHA Troops bases, the 5th mission I think, it's after Riposte's Primer.