I'm almost certain that Snow Leopard woke up from sleep on a 2010 Macbook Pro faster than Mojave wakes up on a 2019, but I don't have proof. It was definitely more reliable.

I learned Python on a white MacBook running Snow Leopard. Those were the days. I don't remember a single instance where it crashed. Super reliable.

The wake from sleep behavior is really bad on modern MBPs, feels like it takes an eternity, too much black screen then the password screen just isn't responsive for a good 10 seconds sometimes.

Actually the power on behavior is bad too, without the chime you can never really tell if the thing is working or not.

10.6 was also Apple's peak server OS. Open Directory + Workgroup Manager set my standard for how OpenLDAP ought to be managed.

Notably, it was also their last server os. OS X server lived on, but as just an app.

Snow Leopard was an entire release dedicated to making Leopard faster and more stable ... so at first glance it makes sense your memory of it is so positive.