Both are excellent scopes. I somewhat prefer TT, but a lot of it is personal preference. The biggest advantages ZCO has are eyebox and daytime resolution.
TT has better contrast which really helps in fading light. It also has a bit more depth of field which, together with the microcontrast, seems to help see through the mirage a bit better.
With every design there is a tug of war between contrast and resolution. ZCO leans a bit more toward resolution. TT leans a bit more toward contrast.
FOV is actually wider on the TT than ZCO when on the same magnification. I've had a chance to measure them side-by-side. The FOV in ZCO specs is slightly overstated. I thought they would have updated that by now, but I just checked and it is the same.
With turrets, ZCO has a nice locking turret. TT has better feel to me (and seemingly to most). The feel of TT turrets is just hypnotic.
Optical performance toward the edge of the adjustment range is a bit more consistent with TT, but both are pretty good in that regard. Probably the best I have seen to date.
ZCO is a shorter scope, so if you plan to ever put a clip-on in front of one, it can be important.
I expect both companies to stand behind their products well, but I have not had a chance to use it.
I have a fair amount of mileage with scopes from both brands and own two TTs.
Reticles are in the eye of the beholder. ZCO reticles do not work especially well for the way I shoot, which is the biggest reason I have not yet picked up a 4-20x50 ZCO.
I like to use the tree for corrections at moderate distances and dial at longer distances. With ZCO reticles, the tree essentially starts 2mrad away from center, which does not really work for me.
ILya