Katsucon has, hands-down, one of the best stage cosplays I've ever participated in. The pre-registration before the con means that you don't have to worry about getting in a line and hoping you'll get in, and lets people plan their skits and reharse well in advance, producing some of the best skits I've ever seen. They ususally take a few entries at the con, to cover dropouts or if they don't get enough pre-regs, but these are also usually reserved for young fans. They have craftmanship judging before the show, and last year they had some really knowedgeable people doing craftmanship (I can't remember her name at the moment.) They took their time with every entry to really look at your costume and talk about how you made it.
Hall cosplay has been different the last 2 years, so I don't know what they'll do this year, probaly what they did last year since it seems to work. If you don't want to get up on stage, you can find the hall cosplay judge, and be judged mostly for craftmanship, but in a one-on-one setting. They announce the winners for Friday, Saturday and Sunday at closing ceremony.