I haven't tried any of these, but, from reading other's reviews, the sound quality isn't that great on se215. Gr07 would be on a completely different level, especially on revealing details of the song. On the other hand, gr07 have a sibilance problem and might not suit someone who's treble-sensitive. se215 are on the darker side and significantly bass-heavy, while gr07 are more neutral. Isolation-wise, se215 are one of the most isolating dynamic driver headphones, while gr07 is somewhat below average; it's quite vented.
Gr07 seem to be the most recommended in this price range. I was choosing iems of similar price just recently, and after digging through the forum for several weeks, I was left choosing between Gr07 and HiFiMan re-400. I decided to buy re-400 because they offer better isolation (given a good seal) and should be comparable in sound quality (but more mid-centric). They are also very comfortable due to their small size and much cheaper than gr07. But I would probably still buy gr07 if not for the price.
