If you want industrial capacity and ability to self-maintain, maybe go with
Bentus.
Assuming it comes with the Bentusi aboard it's probably about as benevolent an ancient precursor as you'll ever find and will actively work to uplift civilization as long as you avoid the stuff like genocide and slavery that tend to irritate them. If you get to replace the Bentusi well, you're
Bentus now and that's hard to beat. Galaxy-spanning FTL, real space STL barely below C, a hull tougher than a moon, beam weaponry for days, some kind of teleportation trading system, and it's extremely hard to find anything that can out-manufacture any Homeworld ships much less the Great Harbor Ship.
Also while scaling in Homeworld is never easy, it's most likely bigger than the Death Star and if not at the very least can fit a Borg Cube in some of its smaller hangar bays.