For my purposes, the 10% off is likely to be better. I believe the zone certificates come with a lot of restrictions on when you can travel, and availability. The 10% off is on any fare, so I can choose which restrictions I could even get a ticket on a more flexible fare.

I am becoming more and more limited as to how long I can spend away from the office. I would lose more money taking a 1/2 day off work than I would save to take an off-peak flight. Also, I could use this when traveling on business, get 1.5 EQMs, and 10% off. 10% off an F or B fare isn't bad! I own my own business, so I get to decide the fare class/class of service/restrictions etc.

Besides, I gave my last zone certificates to my receptionist. Her mother has all the time in the world to travel, but very little money. Sometimes the goodwill of employees is priceless. I am also teaching them to be more savvy when they travel, even though they don't travel very much.