Yeah, the biggest advantage to a Selmer Mark VI is the fast and comfortable keywork. It's the best I've played in this area. Of the horns you listed, please consider the 1940's and 1950's horns first, as they all started downhill at some point in the 1960's. Conn 10M is superior to the 16M, incidently. (16M is a student horn). Having learned on a 5 digit Selmer Mark VI, I find the keywork somewhat clunky on all these, but could get used to any of them. I love the big sound of the Super 20 and the 10M and the beautiful tone of The Martin tenor. I borrowed a 1940's Martin once for use with my dance band and I still sounded like me. Good Luck.