I always thought that Archie and Al were relatable characters: both are (lower) middle class, both are used to the way things are and both don't seem to me to be really adaptable to change. Additionally, they're "real", i.e., everyone knows people like them in real life. I know Ed O'Neill said that he based portrayal of Al's character on his uncle. However, I wonder if the above similarities are deliberate. E.g., were the writers or even Ed seeing in Al Bundy an Archie Bunker of the 80's? or is it perhaps a pure coincidence?

Similar yet really different. The actor's comedy approach for each actor was completely different which makes them opposites. Married With Children had countless cattle calls for Al Bundy and they could not make a selection. I saw an interview with Ed that stated everyone auditioning for Al Bundy was acting like Jackie Gleason in the Honeymooners or Archie Bunker. Ed came in with a real dry sense of humor which worked. I dont think Archie would have worked with a dry sense of humor. In fact Archie rarely was trying to be funny. It was his antics, bigotry, and racism what made him funny. Al Bundy was always doing dry humor.
Their backgrounds may be similar but they are totally opposite characters when you think about it.

While they may relate, they were VERY different! Archie was a man who couldn't even say the word "breast" or "pregnant", while Al was always talking about "hooters" lol I think Archie would look at Al as low-class honestly, even though they may share some quality time in agreement on certain issues over a beer from time to time