I've owned them both and have formed some strengths and weaknesses for each.
It all boils down to what sort of riding you like to do because each bike is so different from the other. It's really like night and day, the difference between the two bikes.
The Honda is sharp and agile with good brakes and a little more agressive riding position.
The Kawi is softer, comfier and has a smoother power delivery down low. If you get the '93 or newer, the ram air kicks ass on the highway.
If you're into long distances and communting for long periods through the city, the Kawasaki is going to be more comfortable. If you're more into aggressive cornering and more spirited quick bursts of riding then go for the Honda. Both bikes are sort of multipurposed bikes, but each has slightly different strenghts.
Any more specific questions?