Wow, that's a tough call but I gotta go with the kid. The drunk is a lot easier to avoid, he will eventually pass out, he will probably spend most of the next day sleeping it off and eventually he will sober up again. The kid is likely to be a brat for the entire trip.
Personally, I haven't had any run-ins with bad kids. For the most part all the kids on the cruises I've been on have been fairly well behaved. I might just have a higher tolerance (or some of the complaining folks may have no tolerance?!?) and I don't have near the crusie experience a lot of the regulars here seem to have, but I have no problem with the kids I've cruised alongside. Some of the adults however.....
I'ld Rather Be Cruisin'
Disney Magic February 4 2006
RCCL Freedom January 20 2008
Disney Wonder October 2009
RCCL Rhapsody of the Seas September 2011
Disney Magic February 2012
Disney Wonder January 2014
Disney Wonder to Hawaii 2015...I hope!