The problem with alt brands is that they rarely do their own thing or even play sets for that matter. It's mostly [18+ lego set] but NotLego(tm)! Almost no other brands have their own themes like Dreamzzz or Ninjago, even simple stuff like fantasy castle is absent. If I just wanted some random MOC I'd just go to rebrickable.
Mega Bloks had the right idea with Dragons and Pyrates but that was decades ago and no one has replicated it since.

I'd gladly consoom other brands so I can give the finger to Lego but no one is making stuff I'm interested in. The only exception has been that viking longboat house but only because it goes well with Lego's Viking Village and doesn't really hold up on its own.