Well, if you're using Logic for the ~100 GB of sounds it comes with and its MIDI editing, there's no sense getting a PC. You'll spend more than the difference between a PC and a Mac just replacing the sounds you already have.
I don't know for sure, but I would guess any of the current 15" MacBook Pro (possibly with the 512GB of storage) would be plenty fast enough. I wouldn't get the 13" machines because they're only dual-core. The 15" all have standard 16GB of memory, which should be fine for quite a while. Use freeze tracks if it starts to sputter.
Also if you're still in school use Apple's education discounts. They're good on Macs and upgrades, even if it only ends up being 6-7%. Their refurb store has the Haswell-generation 15" model for $1699. It's not a particularly good deal
considering the age of the hardware, but it has a 1-year warranty same as new. Also, you can upgrade the SSD wiht a model from OWC. The Touch Bar models all have soldered NAND, so you're stuck with whatever was on the board when you bought it.