reminder/to do apps

[bikerchk]

I have a disease that affects my cognative so a good "reminder"/"to do" app is very important to me. I have looked into several apps but NEED one that has CUSTOMIZABLE rings for different priority reminders/tasks (not just one ring). I need one ring for a high priority task another different ring for a medium priority task and so on... plus I need to be able to do repeating reminders/tasks and customize the days/weeks and so on - has anyone come across a good, very customizable reminder/to do app? thankyou!