I use Google Tasks as my primary ToDo list. I switched a month or two ago upon finding out that there's no decent Teuxdeux app for Android, and now I appreciate it for other reasons.
On Android, I use GTasks, by DATO.
This morning, they pushed an update, which broke certain features, and this resulted in a lot of negative feedback from folks who, like myself, rely on it for daily task management. Within hours, they had pushed a new release which reverted the breakage.
I'm hugely impressed with the app itself, and also with their responsiveness. I'm also delighted with the Google Play Store, which allows for this kind of responsiveness. From what I understand, in the Apple App Store, it would have taken several more days to get the fixed version pushed out, and I would have been unable to use my to-do list until next week, at best.
So, thanks to all the players in this particular scene. If you're looking for a todo list manager, I can't recommend anything higher. Oh, and there's an iOS version, too, but it's not nearly as nice.