As a franchise, the team the Seahawks have played the most is...

[Wolvie]

The Denver Broncos

Seattle Seahawks Head-to-Head Records - Pro-Football-Reference.com

 

[LoftonPack80]

Yep. This was a pretty big rivalry during the 80s when both teams were in the AFC West. Always enjoyed watching these games as a kid. They never disappointed.

 

[TheDman875]

Man the Chiefs and Broncos were definitely a thorn in our ass for a lot of years. I was never optimistic when the Seahawks were playing in Arrowhead or Mile High all those years. Seeing Elway up in that booth will get the old AFC West blood going a bit in 2 weeks.

 

[Brees#1]

Probably because the broncos were around longer than the chiefs or raiders.

 

[Sharkonabicycle]

The whole AFC West back then had great rivals. The Chargers were kind of bleh, but the Seahawks/Raiders/Broncos/Chiefs games were always ridiculously epic.

I STILL remember the Largent 'play'. Probably the best revenge LEGIT tackle in NFL history.

https://www.youtube.com/watch?v=KKHKtkct5Hwhttps://www.youtube.com/watch?v=LMmQkNT65Do

 

[SeattleCoug]

Yup Seattle got their first playoff win in franchise history in 1983 against Denver. Denver then stole the division by winning in Seattle on the final week the next year.
Your avatar says it all Wolverine.