Cheap cogs eat hubs.

EAI, Dura-ace, and Campagnolo (if you can find them) have worked out well for me. I hear that Phil Wood will be releasing the next iteration of their cogs soon.

FWIW, I used to use Soma cogs, but I was at the LBS the other day looking at cogs and the Soma cog quality has REALLY taken a dive. Travis (Freewheel hayes) said that he wouldn't even sell them unless someone is super insistant. They look like hub killers IMO...