Lightweight, classy, smooth, thumbhole, titanium = Sage 2
heavy (kinda), beefy (kinda), flipper, assisted, tactical (kinda) = ZT 566
which do you like more.
Comes down to looks really, or weight, or size. They are both very good knives.
One thing that might sway you is that ZT has a blade replacement policy. I find that very comforting sometimes!