I'd say it depends more on your knowledge of cars and their workings than anything else.
That 5 year old thing is likely to need more work than the new one. If you can happily deal with small niggling faults with it, then I'd go for that.
If it was me I'd have to go for a new car, as I really don't know that much about cars (compared especially to my dad, who built one when he was my age
). But if you know enough to keep an older one in check, go for that.