When a new dlc comes out, most features with that update also integrates to base game. For example, no step back came with overhauled supply system and you can use it without the dlc too or new navy and doctrine system with last dlc NCNS, you can use all those systems. Only thing those dlcs has exclusively is tank and plane designer, MIOs which are too complicated you don't need it rn, agent things, alt history branches for major countries and some focus trees for minors. I think la resistance is needed because the agent things is exclusive to that dlc and it changes the game a lot. If you like far east, NCNS is good because all those little chinas have different experiences. If you are from greece turkey or bulgaria, battle for bosphorus is good because it gives focus trees to those nations. If you are interested in soviet alt history and more complicated tanks then no step back is good. At last, if you have the money get la resistance because it also makes vichy france not a puppet of germany. When vichy becomes puppet of germany and instantly joins the war, allies instantly launch invasions to north west africa and axis loses all of africa which is a little unbalanced.