Good luck with that one. I've got the H80, the predecessor to yours, and I couldn't find any fans that ran at the same speed or had the same airflow as the fans that came with it, because they are far from stock. Stock fans run about 800-1200rpm.
You have more to worry about than just CFM and RPM. You also have to take into consideration static air pressure. If the static air pressure sucks, your whole setup sucks. I have been wondering the same and came across a video from Linus Tech tips that seems to help a bit. He recommends Noctua NF-F12's. https://www.youtube.com/watch?v=u8HsjgtMzEg
Though I still wonder what the difference of of a h100i would be between 2x fans or 4x fans.