The ZX-6R (I've had two of them, but I only have a couple of non-digital photos of my first one).
The Aprilia was too new and expensive to take on a track, but far too focussed for road-riding.
The VFR was too far the other way; it cost me peanuts and ran for years without ever putting a foot wrong, but it just wasn't involving enough.
The 6R was just perfect - it was big enough that I could ride it down to Dijon without any aches or pains and it could take a pillion or a 4-man tent strapped over the pillion seat with ease. It had enough low down and mid-range to be easy to ride through traffic (even in central London), but when you wound it up (or took it on a trackday) it was still a bloody quick bike.
When I get another bike it will almost certainly be another ZX.
Edited to add: Before the 6R I had a CBR-400RR NC29, which was also a nice bike, but physically a bit small and a bit high-revving for longer journeys.
Further edited to add: I don't think I have any pictures at all of the CBR4, but it was the same colour scheme as this one:
I'd forgotten what a good looking little bike it was, actually.