I use a regular (stickered) QJ. It is awfully easy to turn (so sometimes I'll be uncertain whether I did an r or an r2, for instance), but it's worth it - my times are so much better with it. It's really really fast. It's the only cube of any size I own that really good speedcubers actually try and like.
My mini QJ is just not fast enough or reliable enough for me. I like the size, but it's just not a good enough cube.