Hi Paula,
I've had my 12" Saxon dob for a few years now and am more than happy with it. That said, from what i've been lead to believe, the mirrors are much the same in these dobs. It just comes down to the extras like finders, focusers, bearings etc. Shop around, you might find a bargain or a special deal going somewhere ( sometimes Andrews will offer free shipping with certain brand scopes )
If I were buying a new dob today, I would be looking for one with a two speed crayford style focuser and good quality bearings. The rest, like eyepieces and finders can be upgraded later.
Peter
BTW, if you dont already have one, I would invest in a good collimator