Given that they were developed with very different audiences in mind, I think comparing the two is a bit ruff. Prime had good animation, and one of the best versions of Starscream we've seen in a long time. It also gave us fantastic characters in Knock Out and Breakdown, and probably one of the best humans in the franchise in Agent Fowler. Other characters, like Ratchet and Wheeljack, were highly enjoyable, and after the more stiff and formal military unit feel of the Autobots of the various Unicron trilogy series, the Autobots finally felt like friends and family again. On the other hand, it wasn't completely without its padding and pacing issues, and the McGuffin chase for the various Cybertronian artifacts went on far too long. RiD2015 also had really great animation (except maybe for faces) and gave us Strongarm (who's one of my favorite new characters in some time). Their version of Grimlock was a lot of fun. The Decepticons, by and large, had really fantastic designs and some excellent voice acting. And while I may be in the minority, I actually found Russel to be a really great human cast member (actually, all my favorite humans--Fowler, Russel, and pretty much all the Rescue Boys humans, come from this continuity). It's frustrating unwillingness to draw connections to the previous series or explain its backstory in a substantial way (we still don't really know what was going on with Grimlock) was a bit of a turn off, though I understand that to be more of a corporate level mandate towards accessibility. It too, had its own filler episodes, and while Team Bee did overall grow closer as the episodes progressed, seemed to be unable to settle on just how mature Sideswipe had become or how much Bee trusted his new team or any number of other character beats that got recycled over and over. So I like them both a lot. And we got some cool toys out of both of them. Forced to chose between the two... I'd probably say Prime. But favorite show for the overall Alligned continuity? I'll say Rescue Bots.