I prefer vintage MTBs myself. But after 50 rigid forks start taking their toll. If I had to buy a modern bike it would be a MTB. I really don't feel at a disadvantage on a vintage steel road bike.
Sometimes too much money on a vintage ride is still a lot less than a new bike. Which goes along with the OP. I would pay more than fmv on a keeper. Not too much more but more. Once you have the object you tend to forget the price. Plus you can't put a value on a hobby. Then it becomes an investment and stops being fun.
I have a Surly ECR. Great bike. No shocks, but huge tires that I run at appr. 20 psi. Fun stuff.
The Yeti is a full squishy. I have fallen hard for off road riding, because it's a hoot.
Don't mind vintage mtbs one bit though....