Here is a report card / eye chart I put together to compare the 5 leading iPhone Twitter clients. Enjoy! Please leave a comment if I’ve made a mistake in any of the rows. Click on the thumbnail to open the full comparison chart.

My current favorite is Tweetie. TwitterFon is the best free option (and the only open source option). Twittelator is the only app with sub group support.

UPDATE 1/16/2009: Updated the chart to include the latest version of each app.

UPDATE 1/18/2009: Reading a tweet by Steve Birney, I realize I need to add offline functionality to the chart. [DONE]

UPDATE: 1/19/2009: Note to self – add Dave Winer’s link format to the list of features.

UPDATE: 1/21/2009: Added several new rows, corrected some inaccuracies.