IME, ALL montanas are pretty floriferous but the old standby montana Rubens is hard to beat for a profusion of pink flowers in spring. Hard to see any foliage when in full bloom :-) And all montanas have some scent as well, depending on siting and specific cultivar - 'Pink Perfection', 'Fragrant Spring' and 'Mayleen' are known to be nicely fragrant - but C. montana var. wilsonii is considered by many to have the most intense and carrying fragrance. Not always easy to find, however.

If I was going to pick only one based on flowering AND fragrance, I'd probably go with 'Pink Perfection'.

Just realize that montanas may have their buds frozen off or the stems get frozen back every year in your zone depending on the severity of the winter and the siting of the plant in your garden. I would definitely give it a go but wanted to warn you of the possibility.