I insist on doing the HFS+ install only if you really can't afford buying an SDD (a 128 GB could do, provided you put as much user data as possible on an HDD instead). If you really want to do it anyway, here's how I did it: I've installed Mojave on APFS then ...
The workstation Quadro cards today I've personally found not to be as far ahead with everything, especially GPU rendering with Redshift or Arnold vs. GeForce cards so it really depends on what kind of work you're doing that's going dictate whether the Quadro cards are going...