Alpha 2 has a big facebook page I run, just look it up with the title. A lot of good players you can set up to play.
To answer your question it’s preference. A3 has more BS in it with walk/crouch cancel infinites, wonky hitboxes, V-ism being over powered, otgs, get grabbed out of guard, fireballs sucked, etc.
A2 has bullshit such as not being able to block low post cc activation if you wasn’t blocking already, alpha counters were very strong but could be countered, customs doing 35-55% with a lvl 1 depending on character, Chun Li was stupid strong.
You will find more players on fightcade playing, but few are usually good. Usually if someone is on for A2 they are decent/good. Both games are fun if you are into it’s style. I don’t play A3 so I can go into much specifics outside what I said (I watched a lot of A3 tournaments).
I will say the tier difference in A3 and isms is huge and some characters are trash, while in A2 the tier differences are small. Even Birdie who is doo doo tier can be used and do well in A2. In comparison in A3 if you use A or X ism you can lose more than half you life taken and lose a chunk of guard with corner guard crush V-isms on block. Very very very few characters are good in A or X-ism and you as a player have to be really good. Foosties are very dominate in A2.
We don’t talk about Alpha 1.
Play both and just see which you like. Everyone I know who loves A3 or A2 have a ton of fun, and that’s what counts. Neither is competitive anymore. A2 is easier to pick up though, you could literally learn both. A3 takes more technique because various v-ism combos you have to learn.