I'm fond of Harlequin rasboras. Nice, bright, shiny, and even tempered.
I personally dislike zebra danios... they zip around the tank like hyperactive fish on crack. Not relaxing or enjoyable for me or the other fish in the tank.
I bet a large school of giant danios would be impressive. I have three, and they are always together and moving, but if I had a tank large enough for a few dozen, it would be something to keep your eyes busy!