Balay ni Bambit has a great comparative analysis of Blogger vs WordPress for those of your who are still at the stage of choosing a back end client for your blogging. She ends up coming down on the side of WordPress (as I think most serious bloggers would – I admit I’m biassed) but points out some of the issues you’ll have if you are making the switch. You might also like to check out her post titled Blogger to WordPress in 13 Not-so-Easy steps if you’re contemplating making the switch.
Comparing Blogger to WordPress
Problogger.net runs on the Genesis Framework
The Genesis Framework empowers you to quickly and easily build incredible websites with WordPress. Genesis provides the secure and search-engine-optimized foundation that takes WordPress to places you never thought it could go.