Has sexy dam redux, impale, trample, exploit a vuln attack crush, and a sweet damroll.
Alligator (Which I've never had...so I'm only speculating, but it seems like if you get it, you pick it, period) has an insanely high damroll, a bite that uses that damroll, lagging attack on water, and can go on land and water.
Aside from those two, I think the rest just depend on your secondary forms, play style, wand status, and whether or not you like it. Most anything that can through out a two ***DEMOLISH*** rake that lags for 1.5 rounds will keep me content.