If you are wanting to mod the bike, I would have to pick the Hayabusa, simply because it has been out longer, there is more experience with it, and there are more parts (both new and used) available. The ZX-14 is kind of an unknown in the 'what is possible with this bike' category. If you are leaving it stock or just doing light mods, like exhaust, tuning, etc, then I would probably go with the Kawi. Or you could wait a couple years and see how things shake out. I doubt Suzuki is going to sit still now.