I highly recommend Apollo Sugar Maple 'Barrett Cole' (sp?)
Very dense branching, not too upright, almost horizatal branching, large leaves. Been said to look like a child in adult's clothing. I have 3 of them in my yard and don't have a single complaint. They are everything a columnar tree should be and also semi-dwarf to boot, reportedly only to 8x25 so even in the smallest garden you can find space. Fall color is a 10. didn't lose a single leaf in summer heat.
Another one of my favorite columnars is Liriodendron tulipifera 'Arnold'. Maturing around 16'x70', these have performed great for me. There are some nearby that have been in the ground a number of years I suppose and they also look good. The fall color is great only my one complaint is this one for some reason or another... the leaves do not fall quickly they turn yellow then brown then stay on the tree til they're all ready to drop. Still a worthwhile tree but not as good as the species for fall foliage for that reason.
Another one I like a lot for quality fine textured foliage and dense branching is European Hornbeam 'Franz Fontaine' Note; variable spelling on that cultivar... some spell it FranS. Other than japanese beetle damage this one is a tough street tree and can make a nice hedge, has that strong wood you're looking for an branching looks nice even in winter. Slow growing!!! Rootballs are small though so may make planting easier for you.
Lets see... I've also got a sugar maple 'Steeple', not quite a true columnar, with an upright oval to 20x70', supposed to be of southern lineage as in Athens GA. Great tree, fall color is not all that. Does fine in the heat extremes as do the Apollos by the way.
I recently saw some Princeton Sentry gingos that went in at a shopping ctr around 4" cal and they had a nice form. In the past I've mentioned how mine looks like a scarecrow but it's only about 1.75" so seeing these does offer some hope for the future.
^^^^ Referring to ginkgo biloba 'Princeton Sentry'
White pine 'fastigiata' 5'x25' ... I made a grouping with them in my small yard