Agree, there is no perfect TBBT character, but that's what makes it work and creates the drama and the fun within the episodes and the story.
I liked Sheldon's mother; because she was almost unflappabable, she was very secure in herself and in her values.
Sheldon was often great, but Amy was perfect when she pulled Sheldon up on his egoistical traits and selfishness. When he visits her in her lab during his enforced holidays and makes fun of her research, I really thought that's it now; they are over. He did a few things that would make half of MN tell her LTB.
My favourite scene between Sheldon and Penny was the gift giving, her giving him the autograph and him with the tens of gift baskets. That's where they really understood each other.
Bernadette was really good, too.
Howard was absolutely creepy; I did not understand how a character like Bernadette would be with him.
The main cast of Leonard, Sheldon and Penny is my favourite; honourable mention to Leonard's mother to say most of her lines with a straight face.
Barry Kripke was fun and President Siebert, too.