Hard to say exactly what made me go for my first gen 1. I had an SV650, naked, which I got cheap from where I worked, Woodford Motorcycles. I hadn't had a bike for a couple of years, and the SV was the first thing that came up. I took it on a week's tour of Wales but found the seat bench-hard, a bit cramped and lacking grunt, having been used to bigger bikes for most of my riding life.
So we ended up with 2 silver gen 1s in the showroom - again, I was looking at a good deal, including them taking back the SV for what I paid for it. So I took one out for a spin and instantly liked it - riding position, comfy seat and loads of grunt. Seemed to handle ok too.
After about 2 hours, I took it back to the showroom (the boss was a bit miffed that I was gone so long, as I was supposed to be working behind the parts counter
) and struck a deal.
My situation is a bit unique. I'm always reluctant to part with a bike who's riding position works for me, as I have a dodgy arm and shoulder and am always scared that I won't get on with even a slight change in something like the bar height or reach. But the Fazer just worked for me straight off the bat.
Cost was another big factor - it's a lot of bike for what you pay. Plus, working at a Yam dealer, I got all parts cheap, and paid nowt for labour on services etc
So, then I gradually came to realise that nothing else would do everything as well as this bike does in a single package - so I'm on my 4th one on the trot (2 sold due to changing circumstances, 1 stolen).
I had a stint at Waltham X m/cs, and got to use a boxeye 6 for a couple of weeks while my thou was in for repairs after an off. I thought the 600 was a great bike, very much in the mould of it's bigger brother, but of course a bit nimbler in the twisties - if I couldn't have afforded to buy my current thou, the 6 would almost definitely have been my 2nd choice, for virtually all the same reasons as I chose the thous.