if you just wanna level up guns and shit i'd recommend the new map, shooter house I think its called, it has its own seperate playlist 2-3 spots below quick play.
6v6, its a VERY tight map similar to nuketown or Shipment but you can learn all the spots within a game and its really good for getting XP and kills quickly however you play - camp a spot or run and gun, both work out about equally (you will die a lot).
i do love the variety, so far when I just wanna kill some shit without thinking i'll play shooter house, if I want the "like battlefield 4 but shittier" experience i play ground war, and NVG is kinda cool for a weirder play