Vegetto stomps. Putting Freeza that high is crazy, since Freeza went straight to his final form to fight Goku despite only knowing he defeated Boo (lets pretend this is a statement from Toriyama so he would obviously be talking about the strongest version of Boo) so only Final Form Freeza would be stronger than Boohan now considering the gap between First Form and Final Form I'd say he's under SSJ Gotenks.