Odds are you won't find too many people with personal experience with both, so I'll just throw this general idea out there.
This may be heretical by mower forum standards, but I don't think brand makes much difference, barring obvious things like widespread reports of customer service telling folks with issues to "go eat it". Model information is much more telling if you're able to obtain a large minimally-biased sample, but that's not too easy either. Nevertheless, every manufacturer has its star units and its duds. Always smart to Google for obvious duds, but in this case there's no real issue.
Given the small information sample we can request on forums or beat down through Google, the best we can do is to look at the price and the sum of the parts. You certainly don't "always get what you pay for", but with mowers I think you pretty much do. It all breaks down to hydros, engine, seat design/rider comfort, and deck design followed by frame configuration and general niceties. Listed order changes by price point.
The Husky you're looking at and the Ex-Mark Lazer Zs are solid on paper. Both have premium pumps/wheel motors for reliable high-speed mowing, both have EVC suspension seats (which is a bigger deal than I'd have suspected) which you'll need to make that speed usable, and both offer various forms of operator isolation which will also be important. The Husky has whole operator platform isolation and the Ex-Mark Lazer Z X-Series has something quite similar. Engines choices are similar. Overall design and geometry is similar, except with the Ex-Mark Lazer Z X-Series you're sitting on the fuel tank which might put you up higher. (Good for static comfort, but not as good for ride quality when pitching from side to side over terrain. How smooth is the lawn?) You're looking at a 1200-1300 lb. mower either way, so they'll both be fit for extreme duty.
Since they're both similar brand showpieces, I'd go by feel at this point. Send your dealer rep away to take a long coffee break and sit on each, alone, for a good while in the showroom and note how each fits your particular ergonomics. Walk around the machines and look for what you might consider points of lesser design vs. the other. Which one hits you best? You can hardly go wrong here.
