This is tough.
If I was going for purely for drills, instruction, hype, and development I'd go Williams. There's a reason why the top NFL guys work with him in the off season. He knows how to develop great WRs.
Before yesterday's news I was going recruiting, motivation, personable, relatability, and route scheming I would have went Mickey.
Mickey would win in sit down interview setting, Uncle Keith would win with on field demonstration.
As a former college WR, I loved watching Uncle Keith in WR indie.