LongJohnCena There are lots of players on PSN as well. You can access the game easily with jailbreaking (including online) a PS3 console. It's really easy, just follow this video
As a result of this jailbreaking, there is significantly more players on PSN compared to Xbox Live. While PSN/XBL are essentially the same game as found on DC in terms of characters/mechanics/etc, there are slight differences between DC and Xbox Live/PSN. One of the main ones being that some normals are glitched, such as during Magento's rom loop. Other ones include damage scaling glitches on Blackheart, the height at which characters come in on incoming after another character has died or been snapped, some combos being almost impossible to do such as Cyclops infinite, Chun infinite, etc. It's small things like that but I think the big one is almost certainly the speed of the game is faster compared to DC and the meta is a bit different as well due to switch glitch basically not being relevant. Your window to do certain things seems a lot tighter. Doing a Sentinel refly on PSN does not feel the same as DC, in my opinion. Not to mention there are some weird things happening with the aspect ratio on those ports.
They aren't bad ports, but they aren't arcade/DC perfect either. They are nice for just picking up the game to have some fun. Generally speaking, the community uses the DC version mainly for tournaments so you would probably want to focus on NullDC Bear or Flycast if you are serious about playing this game and don't have access to offline players.
Flycast has it's own set of issues with dropping inputs but it's alright for just playing around and figuring things out. Hopefully that will be fixed soon.
As long as you aren't using the PS2 port, you're good! lol :p