As I have often said, I am one who "eats to live", rather than "lives to eat", so I have only tried octopus (calamari) about twice.
Too much like chewing on a Goodyear or Firestone product. I had to fins a discreet way to eject the calamari into my napkin..

Far be it for me to correct anyone

, but calamari is squid, not octopus.

And I, for one, love both!

if you order one or the other and it is chewie, it was cooked incorrectly. Unfortunately over cooking is the norm in many places that serve them...

I usually order fried calamari as an appetizer when I go out. I would venture to say that most restaurants usually serve calamari that is prepackaged, breaded and frozen, rather then freshly prepared.
Octopus is harder to find. The best I ever had was at a large hotel restaurant in Florida when attending my MC Club's national meeting. It was more tender then ocean scallops usually are.