Super Mystery Dungeon was really bad, at least to me. The story was just boring and it really felt like a game made for really little kids with the dialogue they used. It drove me nuts. I sold my copy.Off the top of my head:
Smash Bros 3DS: I bought it due to hype but fighting type games just aren't for me. I think my friend got more use out of it when my anime club had a get together a few years ago and everyone was playing Smash 3DS with each other but he only had the Wii U version. I just lent him my whole 3DS so he could join them.
Pokemon Super Mystery Dungeon: I thought I'd like the mystery dungeon games but I couldn't really get into this one. It was my first one of the series so I don't know if the series just isn't for me or just this specific game was meh.
Cattails: It's a cute looking indie game but for whatever reason I can't catch food to save my life so I basically just keep dying right at the beginning. I hope to give it another try in the future but I remember being frustrated by it.
I really liked Mystery Dungeon Blue Rescue Team. That was my first and imo it was far better. That said, I've also heard that Explorers of Sky is the best game in the series. I haven't played it to confirm that though.