Having replaced my MacBook with a Mac Mini, I would reconsider. The MacBook is just such a _complete_ package. Great speakers, great keyboard, fantastic screen, the fingerprint sensor thingy.. Takes a lot of gear to match that
If your computer never leaves your desk, the iMac is pretty competitive with those features. Even comes with a TouchID keyboard.
I thought the question was low-end MacBook + mini vs high-end MacBook. The low-end one has all those nice things. I wouldn't sacrifice that. If it has to be MacBook + super old used mini as home server, so be it.