just hit rank 55 today, out of like 38 guns i've only maxxed out like... 6 of them so getting them all to cap will probably take me all the way through the battle pass for season 1 at least.
Still have no clue what is an "OP" gun, the SPR 208 is definitely awesome but you fuck up the aim a little and you are getting clocked every time, I still really like SMGs and ARs for mid range fights. They definitely have to nerf SPR at some point though, its basically a combo sniper and shotgun
I'm still running mostly no attachment guns, maybe a red dot optic and a bigger mag but thats it. might try this load out though, I really do like the M4