Team Spirit player Denis "Larl" Sigitov released a tier list of the best midlaners of Dota 2 patch 7.39b. He chose 16 heroes and rated them by power level. He also advised focusing on personal style of play, and not just on the tier list. This was released on the organization's official YouTube channel.
Larl also recorded a detailed guide to playing his role. In the video, Sigitov gave useful advice on the game, talked about the specifics of the laning stage and much more. You can find it on Spirit's YouTube channel with English subtitles.
Earlier, Parivision midlaner Volodymyr "No[o]ne" Minenko recommended his heroes of choice for the same role. His picks were quite different: For example, he highly rated Lina, which wasn't on Larl's list. You can find more details at the link below.