Tokina 10-17mm vs Canon 10-22mm on a Canon 7d

Hi, I'm looking at getting a wide angle lense (I can only afford one wide angle and one macro set-up atm, so both is not an option). The top 2 contenders seem to be the Tokina 10-17mm and the Canon 10-22mm. I hope to shoot larger animals like whales, sharks, large schools and to a lesser extend some reefscapes and wrecks. The Tokina seems to be the more popular lense, but I'm concerned about the ballooning that comes with the fish eye effect. Any advice or experience is appreciated.

Thanks.

Locking this topic as it is also posted in Photography Gear and Technique forum.  Please only post in one place I will delete your other duplicate post.