Well if you disliked 3/4ths of that cast, the original has to be better, right?
The warrior is a great way to introduce the game to friends, and the 3 other heroes have interesting mechanics ^^
But Welcome Back to the Dungeon have Special Monsters. I didn't play with them yet, but it can be a cool addition !
It's 2 little games, can't you just buy the two to have all the goods ?