The OP did not say "compete" but rather "compare." And comparing the two games is absolutely appropriate and justified. If a smaller and less wealthy studio like Owlcat can provide all of that richness and diversity of options in their game, a Larian game that does not do the same will inevitably be evaluated as being inferior.
Warlords Battlecry 3 has much more races than Warcraft 3, more units, longer campaign, much richer hero customization and build, but it is better than Warcraft 3? Definitely no.
Quality and quantity are totally different things. Following your reasoning, TES: Daggerfall is the best game ever made.
Another thing is, how much fun BG 3 will deliver to a player? How about replayability? You can't just say ''this game is better because it has 5 more races and 10 more classes''.
As for me, i have played Pathfinder: KIngmaker and it was a decent game, but i had much more fun in D:OS 1 and 2 or even Pillars of Eternity.
If we take into acount the saying ''you're as good as your last game'' - Larian is definitely a winner to me.
