Comparison of iPhone Survey or Poll Applications - Which is the best?

I wanted to create a survey to allow program participants to fill out an evaluation. I wanted this survey to be available for the iPod touch (and also iPhone or iPad) as that is what the students involved will be using. There are quite a few options out there so I wanted to know which survey application was the best.

I still haven't made up my mind, but I did create a very rough guide comparing some of the features of the survey apps I found.

You can view the whole survey comparison chart on this Google Spreadsheet.

The chart is also embedded below.

Please add your thoughts and experiences to the comments. Thanks!