Therrin, don't you just love getting jobs where it is virtually impossible to make everything right? And the client always seems to say something like "just make it look good"!
For what it's worth, here are our suggestions.
Knock the dead stump portion out of the Siberian elm and check to see what's going on there. The base of that tree doesn't look that great from the pics. (Included bark and slime flux, typical elm stuff.) Deadwood removal is good and then structure with an eye toward reduction to encourage more lateral, lower growth. You are not going to be able to separate the two trees entirely, but that endeavor should be guiding your choices.
Same with the ash (maple? so hard to tell in the pic). Both trees are too leggy. Neither tree is a good enough specimen to recommend as a stand alone (one over the other). (In our humble opinion.)
Good luck.
D and S Mc