I'm sure it's not intended that way but it could be a trick question

Well, personal opinion: For what they are, without taking anything away from the excellent knife the ZT is, my preference goes with the CQC-7.
When I don't have to wave it, I like to ride the thumbstud when I open my folders and this is one of the reasons I prefer liner lock before frame locks.
Also I think chisel grind cuts better than flat grind and if possible I'd go with tanto shape with chisel grind.
620 is an excellent knife, I find it slightly overbuild but I absolutely love it. Great, just a right size ergos for my hand, solid action and lock, bearings ( that I really don't care about in such knife),
it flips great with thumb action only. Well balanced and actually a millimeter and so If I'm not mistaking, thinner handle than the CQC.
Still, the Emerson have smaller footprint, carries easily, thinner blade for better penetration and great neutral profile of the handle, feels fine with every grip.
I hope I was able to provide the info you're looking for