Hmm... That's a tough one.
I think I prefer raspberries. It's just easier to get ones that are sweet without being WAY too soft.
Also they look really cool.
I'm not too picky, I just get what I get and don't complain, because delicious things are delicious anyways. If I had to pick tho, I think I'd pick blackberries, because I just love how tart they can be.