I also have OBS and I love how it records, except a few issues I experience (hotkeyes don't work) but I don't like how it saves the recordings as flv files. They don't work when I try to use another program to open them and I'm unable to use Windows Movie Maker.
Edit: So I open the settings and I see these options: flv, mp4, mov, mkv, ts, and m3u8. Which of these is best?