I need a reliable used car for $5K. What would you buy?

Stay away from any sport models. Keep it under 100K miles (the lower the better). Something with impeccable maintenance records. Models with longevity are both easier to maintain and have better reliability (i.e. all the design and engineering flaws have long been remedied).

Also models designed to be fleet vehicles may be an option. Do a search on the net for issues with all those makes and models you are interested in. I can say that I see many transmission issues with the famous Ford Explorer's auto trans so stay away from the Explorer automatic.

A minivan might be a good idea as it may be easier to get in and out of without too much effort.

A late model Buick LeSabre or Century would suit you well. They're reliable, comfortable, and a well-kept example should be very easy to find. They're not sexy, but they'll get the job done.