If you’re only in for a month, you don’t have the infrastructure to really support 4s. Specifically, you need to pay 120 CP per 4 cover, or you need to pull it randomly from legend packs. You can improve your odds by gold-starring a particular 4*, but you’re just not generating that many legend packs to begin with at your point of play.
On the other hand, if you really like a 4* - 4s have better damage when covered and leveled (unless you have a really awful 4), so hey, whatever, right?
Other comments -
2* Daken at 3/5/5, Wolverine at 3/5/5, Magneto at 3/5/5 (if you use with Storm, you won’t use blue much anyways, and blue doesn’t generate AP), Storm at 5/5/3 (Windstorm is amazing), Captain America at 3/5/5 (19 yellow?! woah), Iron Man 1* at 5/3/3 (blue is slow to come), Moonstone at 3/5/5 (Gravity Warp is harder to control the more colors it can target, red does pretty good damage considering, and black steal is nice)
3* land - well there’s a reason why players use 3* Strange and 3* Thanos. The team kills stuff fast, and speed is important in PvP. Then they can switch to another team when they want to do defense, or they can shield or whatever, but PvP changes, who knows these days.
Of the rostered 3*s, Psylocke is still kind of slow even after the recent buffs. Hood is fragile. (Sure you can protect Hood with Deadpool or something but even so). Sentry you can abuse but he eats health packs like crazy. Spider-Man is slow. I’m not sure I would recommend any of them for PvP.
I don’t really do PvP though, so I’m sure others will offer better advice.
For your list, just remember the AI isn’t good at using a lot of powers. 3* Iron Fist I think I’d try to keep.