which 6sn7 gives the most air??

bopper,
Go to head-fi.org and read The Reference 6sn7 Thread. They list all the 6sn7 tubes and pretty accurately describe how they sound.

I have collected just about all the best 6sn7 over the years.
Top end air, Tung-sol round plates or Sylvania 6sn7w tubes.
The Ken-rad VT-231 staggered plates have great bass and have more of an airy midrange than treble.

The Sylvania 52'GT(bad boys) are beautiful sounding tubes and probably my favorites. I know everybody loves the Tung-sol, but IMS the bad boys just sound perfect.

The Brimar CV1988 6sn7GTY are really nice too.

  

The Ken-Rads either clear or black glass sound the same to me. Most importantly is make sure they have staggered plates those are the good ones.

Bopper,
Make sure they have three holes in their plates to be real . Sylvania made 1952 6SN7GT tubes with two holes in the plates, but they are not bad boys