Love of the breed. My first breeding cat (Russian Blue) was gotten because of my first HHP, Mitten - blue ticked mackeral tabby with a hint of aby in him and bright GREEN eyes. The RB's have that same eye color.
The rexes were cause they were such cool cats and very people oriented. I loved breeding nice cats (some were shown, some remained as pets). I was considering the judging program for awhile and you have to breed and show cats to grand champions in order to get in the judging program.