A heavy duty 1/2 rack is nothing to sneeze at, but if you've got the space, and aren't going to move it often, get a full rack. The ancillary attachments feel more stable, the pully systems too. I also like the feeling of using different types of safeties (pipe and pin, webbing type, etc....). You can also set up for things like TRXs, bands, rings, pin presses, and weighted isometrics in full rack easier.
Half racks work best if you need to move things around or you might need a few extra inches of free floor space sometimes. Also if you're one of those people that feel caged in or restricted working in a rack.
