This is in the iPhone/iPod touch forum.
Safari is probably the best simply because Apple has a cool bunch of features built in that can't be used by other app developers (for security purposes I assume). That being said for some reason I've been using Opera Mini for months now. It compresses websites on Opera's servers before sending you an image of the website. Over 2-3 months I've used 76% less data for web browsing (119.3 MB vs 482.2 MB). I think the main reason though is, similar to Google Chrome where it shows your visited/favourited when you log on, Opera Mini shows your favourited/bookmarked websites so I can easily hit up the websites I visit often.