If anyone is curious why I picked Saweetie despite her actual lyrics rarely being clever, there is a level of sophistication to her flow and delivery that really amps up the skill rating for me.
I'm not saying Minaj, Thee Stallion and Azalea can't hold their own in flow but Saweetie's flow is so skilled that she can be saying literally anything in a rap and it will sound liquid. That is a skill I highly value.
You will struggle to find a rapper who can spit this liquid over a beat:
It's about the way your mind involuntarily gets hypnotised by the pacing, it doesn't matter how simplistic the actual lyrics are, it's about extremely sophisticated rhyme scheme and delivery patterns in every single song, consistently.