For me, it was the first ZX6Rs (F1 and F2).
I've owned a range of bikes, and during the late 90s I got to try out almost every new bike while I was helping out at a tuning company, but for someone of my size and weight (only about 65kg) the ZX6R was a fantastically balanced and secure feeling bike.
I now ride a VTR1000 because I'm only riding around town and sometimes have a pillion, where the torque and sitting position are ideal for this purpose, but it wallows around on bumpy corners, while the ZX6R was always tight feeling with wonderful feedback, and using it on track days gave me my first sense of what it must be like to ride a 'real' race bike, using the tactile feedback to guage traction, and letting me apply my understanding of the physics involved, rather than that 'seperated' feeling that so many road bikes give.
I suppose it's how you gauge 'handling', but I was so impressed with the ZX6R's that I bought a new one after clocking up 18,000miles in a year around central London and one trip to the south of France. I find that the feedback aspect of handling is so important for inner city riding, where treacherous road conditions and unobservent drivers and pedestrians make every safe arrival a miracle.
I've not ridden any other bike that (for my physique) matches this, and I'd add that the VTR is unimpressive in this respect. It requires re-engineered front forks to make them less prone to locked shims (an expense that most riders wouldn't consider or be aware was required), and even then has nowhere near the sense of 'oneness' that I got with the ZX6R.
Cheers,
Jason
