I use a few different ones because different people/dealers don't use them all.
Do a very broad search and filter only a bit at a time. You can find really good deals sometimes when you aren't filtering too much.
I prefer a few year old vehicle with lower miles over a newer one to let someone else take the depreciation. I used to only buy new, but one day I realized that I was trading in perfectly good vehicles with lower mileage. Sometimes, it was to get something different, and sometimes because my needs changed. Of course, a lower cost vehicle will usually have less expensive insurance. As long as they have documented history of maintenance via CarFax or similar, they are most likely just fine. You can make a guess what they were used for and where they were used to avoid areas with lots of road salt, etc.