Greater Constraints
Owning both with generally the same apps or similar apps I have to say I find more and more that Android is more usable.
Especially with iOS5.x, the constraints on what/where/when/how aligning you more and more toward the iCloud is severely limiting app functionality. So they may look similar, they may function similar, but the under the hood and options are not equal.
Good example: on my iPad I used to create / change / display work docs using iWorks with Dropbox and Skydrive as my "cloud". iOS5 came along and while some functionality remains, the flexibility has been removed and steered toward the iCloud. On my Transformer, using Polaris or QOPro (QO is also on my iPad) I still have full flexibility.
Controlled vs. Options
I'll take options any day.
