If you like to work on your own stuff, or are willing to learn, then vintage bikes make sense -
If you're a careful shopper, you can get a lot of bang for the buck.
OTOH, if you're the kind of person that runs to the shop for every little mechanical glitch, to get your brake pads changed, etc, etc,
then the the newer the better is what you should look for - The bike shop will be more likely, and able to deal with it.
You need to be honest with yourself.