I grew up calling him Father Christmas, and have the same emotional connection to it as you've described. Santa just doesn't do it for me, it just sounds commercial. DF on the other hand has a surname that is very similar sounding to Claus, so they used to call him Santa C...as if he were part of their family.

I suspect that I'll start by using Father Christmas, but DF will use Santa, so DS will probably grow up with a bit of both, although if I'm realistic, I think it will default to Santa eventually. But I'll fight it for a while