For the longest time I've used
NetNewsWire Lite 2.0.1 for reading RSS and Atom feeds. Lately, I've been trying out
Vienna for Mac OS X... and I like it for a basic reader. It has all the features of NetNewsWire Lite (that I like) and a few extras, but not all of the features of NetNewsWire (the full version).
Update: Hmmm.... I can't say if this was Vienna acting on its own or getting pwn'd by page content, but a few times Little Snitch caught Vienna trying to contact https://www.paypal.com. Also, there seems to be some other security related issues, because Vienna crashed a few times while rendering pages. BTW, nothing exotic here just regular reading. I've since switched back to NetNewsWire Lite. Maybe one day I'll pony up for the full version of NetNewsWire. 
