What would you do?

My husband and I live in western Washington, and are preparing to get AC installed in our 2400sq ft home. Our furnace will only accommodate a single stage unit unless we upgrade, which we don’t want to do as the furnace is relatively new (though we aren’t opposed to a non-single stage unit for when we do replace the furnace down the road, even if we can’t take advantage of it right now)

We know for sure we are going to go with a 4 ton unit, but are torn on AC vs heat pump, and whether or not the SEER rating is enough to justify higher costs. We have quotes ranging from 11.5k to 20k with a variety of SEER ratings (14-20) AC or heat pump, and single/multi/two stage / variable speed.

Thoughts? Thanks!