If you're looking for manga similar to Futagami Double, you might like these titles. All recommendations are made by Anime-Planet users like you!
Some time before Otonashi made his way into the lives of Yuri and the gang, and prior to the creation of the SSS, Hinata is involved in a car crash and wakes up in life after death. Surrounded by strange classmates in a strange school, he quickly meets Yuri and, after giving her the nickname Yurippe, the two begin to plan out their fight against god. That is, if they can figure out how to deal with the student council president...
This is a pure gut recommendation since I will never real the Angel Beats manga. But Futagami Double gave me a similar feel because of the anime. Supernatural students fighting against something that is of a higher power than them but they might possibly defeat it. Just read Futagami Double if you liked Angel Beats and vise versa. I'm sure you'll enjoy.