My fav is action driver, it was Comet racer originally but after trying AD I impulse buyed the last donut games missing in my collection, Alice Greenfingers was one of those games and now sits as my second fav donut game. Love almost all of them, great little time wasters!
Bubble Pig has FLOWN up to the top (or pretty damn close) to my favorite game of theirs. The level designs are perfect. Very tough, but not impossible to 3-star.
I'd go with Cat Physics. I contacted Donut Games awhile ago and they insinuated that they'd pretty much be concentrating on porting all of their titles to the Android for now, and that they'd eventually get back to the iPhone/iPad to produce brand new games or perhaps sequels.
