For me, it's OS X, hands down.
I love Classic Mac OS, but in my view the fact that OS X is so much more stable is enough to make it #1, without even considering all the other aspects in which it rocks.
My least favorite Mac OS version, I think, is 7.5.x. It's slower and less stable than 7.6.x, and more complex and RAM-hungry than 7/7.1. Also, if you want the OS 8-style Platinum appearance in OS 7, you can do it with 7.1. So all in all there's really no need to use 7.5, except that it has relatively modern networking built-in and it's free.
M
I love Classic Mac OS, but in my view the fact that OS X is so much more stable is enough to make it #1, without even considering all the other aspects in which it rocks.
My least favorite Mac OS version, I think, is 7.5.x. It's slower and less stable than 7.6.x, and more complex and RAM-hungry than 7/7.1. Also, if you want the OS 8-style Platinum appearance in OS 7, you can do it with 7.1. So all in all there's really no need to use 7.5, except that it has relatively modern networking built-in and it's free.
M