The choice of values (what to measure) certainly has many subjective components. That said, a good chunk of people tend to value (to some degree or another): cost of ownership, reliability, fuel economy, performance, appearance, seating/cargo capacity, and resale value. Many of these criteria can be measured, more-or-less, in objective ways. Some criteria tend to vary more across individuals (such as appearance or driver "feel").

I mention this because if a person states their preferences across the attributes they value in a vehicle, it is quite feasible to have a detailed (if not "objective" then at least a rather neutral-point-of-view) discussion about the matching set of vehicles and what they offer across the dimensions.