In my opinion dragon quest builders is the better option. I've played both games to know that dragon quest builders offers more. Also, the concept of Portal Knights isn't greatly delivered
I played DQB and i loved it! The story is ok, the characters are funny and it's pretty relaxing. Sure u fight monsters, but beside that it's a nice experience where u can relax on the couch while building, mining and gathering resources! Also, for me was a little addictive xD