Total Recommendations: 3
Both of them are created by the same author, and honestly, Rave is much, much, much, much better than the other. First thing first, Rave has a plot that actually fucking moves. It also has character with actual 'character'. And the best part: the girl isn't just there for your fapping purpose (don't worry tho, their boobs are still bigger than your dream). Don't get me wrong, Rave definitely isn't the best of the bunch, it's still pretty cliche and 'shounenish', but if I can I would just pretend that Rave is the only series that Mashima worked on.
Re:Zero and Steins;Gate featured an MC with similiar power: time travel. And the 'time travel' aspect of these series isn't just some cool sci-fi material, it has a little dark element attached to it: 'death'. Both MC tried to save people around them from the hand of the reaper, they also touched upon the psychological aspect of the MC as the only one who remember the events from before the timeline is altered. Also, both series are produced by the same studio and have fantastic, fluid animation. However, while Steins;Gate is a bit slow on the beginning, Re:Zero show its dark element right on the very first ep.
This is a recommendation made based on how the MC resemble each other, and to some extent, lead how the story is going to progress. Both series featured a young boy who is shunned and looked down by society, and thus driving them to proved those stigma wrong by becoming 'the best'. It's an intriguing coming-of-age-type stories that will make you rooted for the MC in order to reach their dream.