Web Worker Daily has published an article about the different web-based Mobile Aggregators and their thoughts on each different solution from Google Reader, Bloglines, Newsgator and others...
Personally I never ever use an online RSS Reader on my mobile device as typically I'm reading RSS feeds in places where I don't have coverage or the patience to wait for page loads.
Instead I use an offline reader... Newsbreak from Ilium Software.
I've tried pretty much all the offline RSS readers and ended up with Newsbreak because of it's rock solid reliability and really clean interface.
The latest version 2.0 even now has support for Podcasts.