Only have pull my finger, but it has a good interface and is kinda funny. Theres a youtube vid i believe that the dev made back when it was rejected from the appstore.
Well, that's a tough one! Pull my Finger has 18 different sounds while iFart Mobile has the "Sneak Attack" and the "Security Fart" functions, both of which are highly usefull. About the sound effects I can safely say that Air-O-Matic (the developers of Pull my Finger) have really outdone themselves trying to recreate realistic sounding... Wait! You can't possibly be serious about this! It's a frickin fart app, dude!
lol that's exactly why I want to know which one is better. Both have some pretty negative reviews, and I want to buy one with better value. Plus, it never gets old!