Well which one is the most realistic?

I guess Arma 3 is the most realistic all around but the fact that it costs like $200 for the full game + DLC it just seems like rip off to me.

Arma:Reforged also pretty nice but no linux support and few players.

Squad - definitely a good one and with mods its very dynamic and it is still getting updates so thats really good despite being 6 years old.

Hell let loose - my persona favourite world war 2 mil sim, but limited in time and scope. But if you like the old Americans vs Germans thing its great. Also little bit historically inaccurate in some instances.

Squad 44 - Dunno anything about it but its contender?

Which would you add and which would you say is the best?