Glad you're experimenting with different bikes. Best way to find out what works best is to just try out different bikes. The benefit with going a bit older, and you really don't even have to go that old to get bikes for cheap, is if you don't like it, you're not in for much money and you can sell it for about the same. It'll also help you figure out what you like aesthetically. Function is key but let's be real, we all (or most of us) want something that looks cool at the same time.
Enjoy the ride and let us know how the retro bike compares to the brand new mtb on the road.