Lots of good suggestions and lots of ways to go. If this was my account and I was returning I would work on putting relics on some existing teams/characters first (GAS, JKR and Jedi like JKL, Qui Gon omicron, CLS, BHs maybe). While working on this I'd work on shard farms to finish the BAM requirements (after Kuiil is done keep going to finish TIE Bomber), Mon Mothma, and Chewpio. With fleet energy I'd work on finishing TIE Eschelon and Greef/Rebel Y-Wing, and starting Outrider after(at most probably can only afford 1 or 2 of these farms at once, I'd prioritize in that order).

I think this gets you caught up a bit on what you currently have then leaves you in a really good spot and gives you some time to consider what to do next; to go finish SLKR, go for Executor, go for JML, go for Profundity, or go for Jabba. I think going for Executor first would be the most beneficial but depending on where you are with acquiring Razor Crest shards, this might not be realistic. So doing a GL first probably would likely be a better option for you. SLKR and JML are great options. I think that Jabba is becoming really important for all game modes and should probably be your second GL. So GL -> Executor (maybe Profundity instead if you go for JML first) -> GL could make a lot of sense. Lots of options!