Lots of good discussion over on the Texas monthly top 50 bbq thread on the food and spirits board if you are ever looking for more bbq info.
Having been to both multiple times, Franklin is definitely better. As said above, Snows still uses lower quality briskets and while theirs are really good and deserve a lot of praise, Franklin is just on another level. Better brisket and ribs, kind of a tie on stuff like sausage, turkey, etc. and snows does have a really good pork steak but thats about it that they have over Franklin.
And while it's kind of cool that Snows has the tradition of being only open on Saturdays, Franklin definitely gets bonus points for cranking out fantastic bbq 6 days a week vs them only doing it one day a week. Both are fun experiences if you tailgate while in line at Franklins, or get a tour of Snows pits and pic with Miss Tootsie.