All of the above for me plus...
5. Ease of access to service points.
6. Cost of ownership.
7. Parts availability/dealer network and support proximity. I service my own equipment, but IMO, it is still important to have dealer support for warranty or recall issues in a reasonable distance. When someone asks my opinion on which mower they should look at, i ask them what brand is supported the best in their area, especially if they do not do their own service/repair.
8. Overall design and quality of the unit and components.