Last night's game would have elevated the Patriots into this:
Best franchises of all-time:
1. Patriots
1a. 49ers
1b. Steelers
But now we're:
1. 49ers
1a. Steelers
3. Packers
3a. Cowboys
5. Patriots
I'm not sure how you did your ranking, but i do note that you are ranking "franchises" and not "teams" (e.g., the Cowboys Franchise has made eight SB appearances, but those appearances were made by different teams and in different eras). also, you leave out franchises that made a good part of their name before the SB era (e.g., Browns and Giants), so i assume you are talking about performance in the SB era.
So, if we are ranking "franchises" "in the SB era," it seems to me that the only objective way to do this is by SB appearances and wins. If we limit the candidates to those franchises who are fortunate enought to breathe the rarefied air of five or more SB appearances, we get this list:
Cowboys: eight appearances, five wins
Steelers: six appearances, five wins
Patriots: six appearances, three wins
Broncos: six appearances, two wins
49ers: five appearances, five wins
Raiders: five appearances, three wins
Redskins: five appearances, three wins
Dolphins: five appearances, two wins
If we limit ourselves to franchises that have won three or more SB's, then we get:
49ers: five wins
Cowboys: five wins
Steelers: five wins
Giants: three wins
Packers: three wins
Patriots: three wins
Raiders: three wins
Redskins: three wins
Both lists are elite and we belong on each.
What this says to me is that, if you are ranking "franchises," getting that fourth SB win was probably the biggest thing we lost on Sunday in terms of breaking away from the pack. Bigger even than losing the Perfect Season.
The question of which "team" is the best is a debate that has been going on in the media for the last few weeks and to which I have nothing to add at this time. You can make that argument in so many different ways by era, cap, free agency, etc. With 19--0, the pats would have been able to lay legitimate claim to that title.