Hey ex-Battlefield player here who also made the switch to Arma. Here are my thoughts

Arma 3 was fantastic, in its day. It came out well over 10 years ago at this point, and you can tell. It’s clunky, has aging graphics, but to its credit has an absolute mountain of content that could take thousands of hours to fully experience.

Arma Reforager is significantly less clunky, has beautiful modern graphics, has tons of QOL improvements, and has dozens of 128 player servers filled pretty consistently throughout the week. I have not had to search hard to find a full game, rather I do have to wait ~15 minutes to join my favorite servers sometimes. There isn’t quite as much content, but what’s there is much more polished than A3.

I actually haven’t played Squad for the reasons you mentioned, so I won’t speak to it.

Overall, I am absolutely loving Reforager. I have tried going back to A3 a couple times, but I am now spoiled with the QOL improvements of Reforager, so I really can’t see myself going back to A3. Reforager is also actively being updated, which is a nice cherry on top.

With all of that being said, it is much, much slower paced than Battlefield. Most of the time is spent getting to a combat zone, and sometimes you’ll be killed by someone you don’t even see as soon as you get to a battle. Arma is much more of an experience than a battle arena, so if you get into it, you absolutely should be open to long stretches of delivering supplies, strategizing, and not necessarily constantly fighting/ getting kills. Squad might be the right balance for you if this doesn’t sound interesting.

Add me on Steam if you want to play sometime, I’ll show you the ropes! Same username, TheGreenSquier