I always try to not let my bias for my favorite hero to come through on this site, but here, I think I can let loose a little bit. Captain America is the most patriotic character out there, in my opinion. He embodies America, both good and bad, even going so far as to go against the government when he feels his patriotic duty calls to. He has always been a character that captures all that is good, noble, and strong within this country and he deserves to be on the top more than any other.
2. The Shield
The Shield is touted as, "America's 1st Patriotic Comic Book Hero." The character has seen many different incarnations, and not all of them were American heroes, but by and large The Shield is as patriotic as it gets. He is the face of America and battles against all who would bring this great country down. He is a classic character that hasn't been used as much as he should, but has seen some new life in recent years when DC Comics licensed The Shield and other characters of The Red Circle, which is a great thing to see.
Captain Britain is the champion of England and the British Isles. He is so tied to his country that his powers actually fade the further he is from his homeland. He is a warrior for the United Kingdom and has always fought to preserve and protect his people above all others.
4. Uncle Sam
He is the mystical embodiment of the spirit of America. He comes through the bodies of slain soldiers and patriots throughout time to aid the good ol' U.S.A. in its most dire time of need. He has even assembled a group of heroes known as the Freedom Fighters to battle against injustice and tyranny all over.
5. Union Jack
Union Jack, super spy of the British Government, holds dear to his heart his Queen and country. He wears the Union flag as part of his costume and as a commitment to the ideals of his country. He is constantly vigilant against those who threaten the freedom of his country.
What does an alien living on Earth have to do with patriotism? Superman has completely taken his human and American identity to heart. Raised in the heartland, he has become what many aspire to be, a truly great man. His nickname by some of his friends is the big blue Boy Scout and while this is a bit of a derogatory statement, it goes to show just how firm he holds to his ideals. While not really an American hero, he holds true to the American ideals of truth and justice for all.
Guardian (also known as Vindicator) is the Canadian version of Captain America. He is the leader of Alpha Flight and serves to protect Canada and its occupants. As a part of Department H, he is charged with keeping all within the borders of Canada safe, and even travels abroad when there is need.
8. Red Guardian
The guardian of mother Russia, Red Guardian has seen many different men wear the mask and hold the shield, but each one has fought for the cause of protecting the land of the hammer and sickle with fervor. Many have even given their lives for the cause. During the Cold War, the Red Guardian was seen more as a villain, but this new incarnation sees him as the hero he was meant to be.