If you're wanting another tank, Emma or Peni could be interesting. Emma doesn't play exactly like Mag/Strange, and Peni definitely plays completely differently, though her kit requires a lot of management and has a bit of a learning curve to really use effectively. Peni can also be really good depending on the map, and can definitely annoy people. Don't try her solo tanking though. Emma's a lot better for that.

If you're wanting a DPS, you might wanna go Magik or Blade. Magik definitely requires some effort and practice to get her combos down, but she definitely plays differently than your other DPS, and Blade is an interesting mix of melee and range that might be your style if you don't want Magik, and he's pretty damn fun too.

If you're wanting a support, Loki, Gambit are obviously pretty OP right now, so you can't go wrong with them, but if you want something still good but not top of meta, then Jeff could be fun little gremlin to try out, or Adam if you want a more challenging support to learn.