Talk to TEM. He bought Beautiful Katamari but said it wasn't as good as the first two. I thoroughly enjoyed all 3 minutes of the BK demo. But it was my first Katamari game. So maybe I should try to track down the impossibly-hard-to-find We <3 Katamari.
As for Table Tennis, based on my totally 360-biased opinion and total lack of research about the Wii version, I imagine the Wii version is a slightly more strategic form of Wii Sports Tennis. With the 360, you get reliable online play, achievements, quality graphics and possibly a more responsive albeit not perfect control scheme. The game gets really hard about halfway through, though, so it takes major huevos to actually beat the game on Expert or even Hard mode, and more huevos when you lose to the same freaking dude by two points for the umpteenth time. However I really enjoy the incredibly deep strategy to the game, and I recommend buying it no matter which version you choose.