The lowest mileage used car is best. This is both in normal car shopping and in collector car shopping.
Normal car shopping I hear it all the time, “I want X car only under 10, 15, 20k miles.” Usually, it’s at the usual used car age of 3-ish years, so most of them are off-lease. In normal times we’ll have a range of mileages available for our popular used cars. Most often the lowest mileage ones come from NY, Chicago, NJ, somewhere that they didn’t need a car much. So they were street parked, banged up, backed into, and the inside was also trashed because likely not having a garage it’s not as easy to clean out. These dumbasses will completely pass on the car that was owned locally, by a couple out in the suburbs, kept in a garage, never street parked, and taken to the cabin on the weekends so it’s got 40k miles. One needs work, one doesn’t, I probably don’t need to tell you which is which.
In collector car shopping it’s also a myth but for a completely different reason. I’m not talking about restored stuff from decades ago, I’m talking about ‘80s and on fun desirable cars. If you buy the one that was never driven and is 20 years old with 10k miles, you’re just paying more for dried out seals, old oil and tires, and other non-use service needed. Not to say you need to buy a 100k+ mile car, but buy the 20 year old Corvette that has 50k miles over the one owned by the old guy thinking it would be a collector and only put on 5k.