Call of the Wild has a 2 second cast time and refreshes in two minutes. It's a "zero percent" rez. So you can rez after and get your experience back.
Staff of the Forbidden rites has a 1 second cast time and refreshes in twenty seconds. It's a 90 percent rez, so you'll lose however much time it takes to kill enough mobs to make up the difference.
If your main tank went down, the one second rez is a good option. You'll probably want to use Call of the Wild next to rez the cleric who went down while the main tank was dead. If you're lucky and your chanter locked everything down, you probably won't need a third rez when that twenty second timer runs down on the Staff of Forbidden rites. To me, the reason the staff wins over Call isn't the 2 second vs. 1 second cast time or 0% vs. 90%, it's the twenty second vs. two minute refresh time.