"I guess the expressions of preference for the Smiths is based on brand loyalty rather than reality."
IF action smoothness were the only consideration, then maybe you might be right.
But you're not.
I've fired any number of Smiths whose actions are very comparable to similar Colts. Yes, it required some work to achieve that. But with a Smith, it's not a difficult job at all. It's a lot more daunting with a Colt.
Sorry, but the Python, given its status and the amount of hand fitting needed to achieve its action, isn't comparable.
My personal preference for Smiths over Colts is based on a couple of things.
Esthetics is high on the list. Sorry, by the Python is one of the ugliest guns ever made. And most Colts look somewhat unfinished with the uncontoured hammer.
Functionality is also big on the list... Specifically, the thumb latch. I HATE Colt's "pull it back" thumb latch. The latch on the Smith is FAR easier to operate. I can thumb the latch on my Smiths and pop the cylinder with my right hand while my left hand is pulling a speedloader out of the pouch.
Can't do that with a Colt.
Last is ergonomics. Colts simply don't sit well in my hands. Smiths sit FAR better.