I'm quite fond of Howard the Duck, which has a good cast and a number of funny lines.
Water World I just thought was terribly boring. It had all the stupid of, say, Tank Girl but none of the cheesy joy. Costner is convinced he's god's gift to cinema (just read an interview where he blathers on about his latest Great White Father flick and confirms the diagnosis), and can't lighten up enough to play "web-footed messiah" as any way other than completely straight.
I've never seen more than bits and pieces of the other two.