My Pista came with Sugino RD's, and it worked just fine.

I now ride with a Stronglight...light and strong, just like the name says.

For prestige and old school aesthetics, Campy Record.

For absolute strength and trueness, Sugino Grand Mighty.

For a high strength to weight ratio and modern aesthetics, Dura Ace.

I saw a fixie built by an instructor at the United Bicycle Institute in Ashland, OR, and he or she put it together with all Dura Ace components.
Gorgeous, strong and light.