I think it's down to personal taste and value.
The chrono at that kind of price, is nothing more than an ETA7750 with some modifications is not what I am prepared to pay.
The Mark although still running on ETA, it's fitted with IWC's proprietary pellaton winding system.
Other forums have been debating about the "in-house-ness" of the movement.
And most importantly, I like less complicated watches.
The chronograph that I own is the Zenith Rainbow Flyback and Zenith Chronomaster Open.
Zenith for me is what chronographs are all about.
Legendary, robust, reliable and tri-compax subdials at 3, 6, and 9 (which I feel is more balanced than 6, 9 and 12.
But in the end, whichever floats your boat bro, coz you'll be the one wearing... it's your money, as long as you're happy with it... we're happy for you.
Try on both and the one that makes your heart beats faster is the one you will bring home.