I personally think I'll prefer this game, Banner Saga is apparently more of a strategy game, you don't create characters etc. Blackguards is heavier on the RPG aspects, the character system is mostly a modified version of the German pencil and paper RPG "The Dark Eye".
That last part has my ears perked up, I love Pen/Pencil and Paper RPGs. I was fond of Realms of Arkania 1-3 and the latter Dark Eye adventure games so that sounds really appealing. I will probably still get Banner Saga just because it looks interesting to me, but the more I see about Blackguards the more I look forward to getting the game.