Personally I like the blue, the purple and the red, but depending on the color of your case... also, just because you've got room for 5 fans doesn't mean you'll be able to see al off them (especially the front intake fans, which i imagine there are two of) in which case you don't need to spend the money on LED fans, and out of the choices here I would go with the Panaflo Ultra Quiet or even the Vantec Stealth. Otherwise, the colored fans at the top of the list are performant enough, though nothing special... mind you, with five fans total I don't think you'd need anything more anyways... The Thermaltake SmartFan 2 is a really good fan by the way, and the one with the "coolmod" is pretty neet, and I would definitely suggest that one out of all of these if you like the look, since it puts-out 75cfm at 45db, and comes with temperature-control and manual fan speed control ability (like a rheostat) for a good enough price.
Have you ever stuck your finger in a Vantec Tornado? That's 5700rpm right there - ouch. Today's public service announcement: don't play with plugged-in fans - especially Tornados..heh.