I think the proper genre term you are searching for is PBR&B. Prince is the Godfather of this genre.
My opinion is:
1: Frank Ocean
2: Miguel
3: The Weeknd
Frank is the best songwriter, he has the most pop appeal, and he has the best co-signs; Jay-Z & Kanye West. Two stellar projects in nostalgia, ULTRA and channel ORANGE. Miguel only has one, his first album sucked terribly despite a number one single. channel ORANGE is in my top two favorite albums ever, despite it’s young age, and he has tons of potential to shake the world. I really think Frank Ocean could go down as one of the greatest musicians to ever walk the planet.
Miguel is like the ghetto Frank Ocean (I couldn’t think of any other way to put it). His songwriting isn’t dumbed-down, but it’s not near as complex as Frank’s. Don’t hold the song “Pussy Is Mine” over my head, it’s a very vulnerable track. His sound is very nostalgic, which is one of the qualities I like about his music.
The Weeknd is the “weirdest” of the three. He’s more alternative than Frank Ocean and Miguel. His sound is less R&B than theirs, and is not soul music whatsoever. Very trippy stuff. I’m not saying it’s bad or I don’t like it, it’s just not on the same level as Miguel.