I have been trying out several Newsfeed apps including; NetNewsWire, Vienna, and others.

Many people cite NetNewsWire as being their favorite app, but I prefer RSSOwl for a few reasons over other apps:
- it's free
- it's fast
- it is very customizable

The only downside is that you need to spend a few minutes doing the tutorial to become familiar with it, because it appears complex at first sight. Once you have educated yourself (about 5-10 minutes), this program reveals itself as easily the best newsreader out there (free, or not).