Eh. I don't hate One Piece, but I've significantly lost interest ever since Arlong was a thing. And like the last crossover, the stupidly large gap in power scales makes it hard to make anything meaningful out of it. I mean, yeah, it's all just for fun and games, but it nags you in the back of your head. They're probably going to have to need some sort of collaborative effort to stop some villain, when you know Raditz can just solo their universe.
Sorry if that seems unnecessarily negative, I'm sure fans of both will enjoy it, but...I'd prefer at least being able to pretend the two crossing over are in the same brackets. Not necessarily in popularity that is, I think One Piece has actually surpassed Dragon Ball in that, which still astounds me, but it's hard to craft a story between an above average guy and a god who play by different universal rules. It's not quite the same deal as a good Batman/Superman story.
Spoiler: Random wish listing (click to see content)
...Though, speaking of crossovers, now that I'm left to think about it, why didn't Dragon Ball and Sailor Moon ever happen? An experiment between a top shonen star and a top shojo star like that would be actually interesting to see how it plays out. The two are still going strong after however many years it's been since they started and both are still seen as the faces of their respective genres by many. Dragon Ball's got this Super revival and Sailor Moon's got their reboot both running, both are big world wide, hell, both are starring in the next Olympics.
Besides, it'd be amusing to watch both Goku and Usagi having the same naïve positive mentality about everything, while one's, like, four times the other's age.
Or if not that, I always found Naruto to be more relatable to Dragon Ball than One Piece, and I'd imagine Toriyama felt the same considering the art swap he took place in with Kishimoto. Not that that's any better a replacement on the power scale to One Piece, but I dunno, feels more natural to fit a crossover into.