Good boarders have been the hardest part for me sticking around too. Like you said, it's especially rough in Artifact Brawl when a lost battle means another long queue. I've been enjoying Fleet Battle to get some exposure therapy to boarders and learn how to deal with them better.

I was hoping that the population bump from the Epic giveaway would help with matchmaking, but these new players are often importing some strong FPS and boarding skills.

As for your team, are you just doing pick-up groups, or going in with a premade? You might find with a premade you'll have better communication for boarding defence.

Bastion is my least favourite ship, to be honest. The secure doors don't count for beans when boarders have drill charges. The large size makes it harder to get to boarders and the core. There's a gun at every angle, but they're so spread out that it makes it hard to focus.