I'm going to have to give the number 1 spot nod to the Road Warriors. Their impact and legacy are still at the top of the heap, and you can't talk tag teams without their name coming up as anything less than definitive. That being said, here are some of my other top teams.
Hart Foundation-great mix of brute strength and technical wrestling
Owen and the Bulldog-see above
The Rockers-these guys just made everything seem so fluid and effortless.
Tully and Arn
The Freebirds
Rock and Roll Express
Midnight Express
Jumping Bomb Angels-I have to give Kidgloves props for including these gals. Too often the females get lost in the mix, but they could honestly do things other teams could only dream of, male or female.
Dudleys-while not one of my top favorites, they were still fun to watch and have succeeded anywhere they went. Not bad for some bigger, not even built, guys.
Steiners
British Bulldogs
Samoans
Demolition
And one of my favorites growing up, but didn't last all that long, was the Can-Am Connection (Rick Martel and Tom Zenk). These guys could work in the ring, and had some good charisma. Kind of seemed to me like a bulkier, bigger guy version of the Rockers.
Powers of Pain
Can't believe anybody hasn't given an honorable mention to the Original Blackjacks.
Harlem Heat
Also can't forget the Killer Bees if you're going to speak of in-ring ability
Rougeaus
I can't believe somebody mentioned the Bushwackers. I mean, seriously? They were fun and kids loved 'em, but that's about it. They were actually much better as a serious team back when they were the Sheepherders and terrorizing people before they became the comedy relief team of the Bushwackers.
I didn't list the Hardys because that's too "new" to me to be old school but they were a good team, not taking anything from them.
E&C- I would classify Edge and Christian as successful singles stars before mentioning the tag team. The team was cool, but not one I would put in the upper echelons of tag team history.
New Age Outlaws-Really? I don't know if this is sad or laughable. I mean, they were a gimmick team that was mostly catchphrases and goofy dancing moves. Definitely not one of the best of all time. There are plenty of teams that would be above them that nobody has mentioned yet, namely the Iron Sheik and Nikolai Volkoff, the Dream Team (Valentine and Beefcake), and even the Hollywood Blondes (Austin and Pillman). You could even make a case for Rhythm and Blues (Valentine and Honky Tonk) and Power and Glory (Hercules and Roma) Hell, if you're going to mention the NAO, why not give props to the B.W.O and the Job Squad?