I would like to know which oj has problemsets to better prepare for ICPC. ICPC being a 5 hour contest requires different set of questions to practice. I see that often Div2/3 contests tend to become typing contests and that is not good for practice. Though very late I realized that codeforces contests were a bad way to prepare for ICPC. I am not saying codeforces contests are bad. They just fail to serve the purpose here. I would like to know apart from the gym contests in codeforces, which I agree is a great way to prepare for ICPC, what OJs you use for practice. I tend to see not everyone with a high rating here has high number of successful submissions in codeforces, which means they must be using other OJs. It will be great for the community to know.
I also want to know although i don't prepare for ICPC.
Kattis has one of the best collections of problems from all levels of ICPC contests.
ICPC archive has almost all previous years regional contests. You can import those problem sets into vjudge.net to simulate contest like environment and practise on old ICPC contests.