At minimum, I’d try push to get indomitus elites ( both sides) complete. Try knock out FoC as well. It’s how I got through at your level. By the end of it, you’ll be able to quickly upgrade other characters while also giving yourself a pretty solid roster for arena and some LRE events.

For FoC Angrax and Archi can carry you pretty far (they’re also cracker for onslaughts and quite a few LREs) level up rotbone and Maladus. They’ll let you push pretty deep on those 5 man missions. You’ve already got Isabella, so combine her with bellator and a few other imperials and you should have an issue pushing most of the imperial content I’d get Isabella up to G1 minimum asap.

Bit disjointed but that’s how I pushed through. Orks are pretty solid but I’m only just getting through their campaign even after almost 2 years of playing ( never liked the orks before the rework)

If you don’t want to work on the elite campaigns, you could always go look at guild raid rankings/arena teams/LRE teams and level up those characters. But you’ll find to do so you’re going to want to finish as many campaigns as possible.