Usually, if you're having this argument, you end up comparing two -not so good- drivers to some thing that's pretty-well built. You're trying to compare motor force to cone area, so in order to have greater motor force, you end up needing to compare something like the Solo X to the Comps. Two total opposite ends of the spectrum. I, personally, think that the Solo X would outplay those comps in the correct box. That's not only relevant to the 'Motor force v. cone area' debate, but simply because the Solo X was the best that Kicker had to offer.
Besides, I don't like the whole 'cone area is king' saying. Though it may have more technical cone area, a 15" square driver isn't going to automatically produce more output than a 15" round driver.
I think more people just need to realize that there is no one factor that will get you a great sub. Pure cone area will not make your sub loud, nor will pure motor force. It's a composition of probably hundreds of factors that get you a nice-sounding, overall well-performing subwoofer setup.