I like Creature a little more than Star Trek Next Gen. And I do like Next Generation, but for me, Creature has:
Slightly better layout. (I'm a sucker for those side shot saucer/holes, ala Space Shuttle.)
Two great themes in one.
Plunger > trigger (always)
More than one true skill shot.
Better video mode.
Just plays a lot smoother. Was never crazy about the cannons in Star Trek, either. But I know some people love 'em.
Star Trek does have more to shoot for, but keep in mind, many aspects of the Next Generation's layout can be found in other machines. If you're a Trekkie, I think Stern Star Trek is the better of the two. Plays a lot smoother with more features packed into a regular-body machine, plus less maintenance than you would have to deal with in Next Generation.