Everyone has different tastes so i agree with Covert, check out some videos on youtube and go by what you like the look of. For me Close quarters is my most played by a mile, even though i didnt thin kit would be for me, but it offers something totally different to the main game, whereas all the others are to a degree more of the same. Notrhing wrong with that obviously and Aftermath and End Game are good also, but it's definitely individual preference.
As for the game modes in each DLC, some may have that a defining factor, whereas other may just go by the better maps.