Niether is going to really be better as they are both about the same price level and have similar material and construction quality. I've owned a Chinook II and extensively handled a 710. The Chinook is S30V, where as the 710 will most likely be D2. I've had some issues with keeping the rust speckles of my D2 knives, so if that's an issue for you, it's something to consider. Both steels are similar in edge retention, S30V will take a finer edge, where D2 is more toothy, both cut well in general use in my experience. The ergonomics on the Chinook are far superior to the 710. The Chinook fits my hand like a glove, on of the most comfortable folders I've ever held, and the G-10 is very secure and grippy, having a very nice quailty feel to it, where as the 710 has flat, stick like ergos and smoother, plasticy feeling G-10. The 710 is much slimmer and lighter and feels better in the pocket, and packs on a mentionworthy amount of cutting edge over the Chinook. Spyderco edge geometry is vastly better than BMs in most cases, and that is not different here, the Chinook will most likely way out slice the 710, especially if you pick up the new flat ground Chinook III. The 710 has the Axis lock, which some will swear by. They are very smooth and fun to use, while being very reilable and strong. The Chinook has the classic lockback, only way beefier. I would trust the lock on this knife over any other, hands down. It's utterly tank-like in lock up. Bouth are ambidestrious, but the Chinook offer four way clip placement where the 710 does not.
Personally, I think the Chinook is vastly superior, and would even call it one of the best designs available right now in folders. The only downsides are weight and thickness.