I have to say, if I was visiting SF, neither would be on my top 5.
But Aqua is more business-y and Mina, just as elegant, but less formal in that sense.
Honestly, though, staying downtown, I'd spend slightly less and go to Ame or Boulevard or I'd go to The Dining Room at the Ritz if I didn't mind a more formal setting.
While I'm not a fan of Aqua ... more for the service ... I would choose it over micael mina if I was a visitor. Why eat at a chain that has restaurants across the country with a similar menu.
That being said, I think Mina does a better job of these chain fine dining restaurants than most celeb chefs like Tower, Puck or Ogden ... gosh, I am sooo disappointed in the Ogden expansion. I loved when he was in the kitchen at Campton Place and the first restaurant he opened on his own. After that ... all downhill
The bottom line ... if I was a vistor to SF, I wouldn't choose either There's better like the Dining Room at the Ritz.