That's a hard question. Objectively, the most well-structured anime I've seen was Fullmetal Alchemist: Brotherhood (I actually met Ed's voice actor). It's definitely on my top 5, but sometimes, it can get a little too deep for me. Same with Evangelion, which is also another one of my favorites. Another anime I like is Hetalia, which is pretty hilarious in my opinion. It's my favorite comedy anime, but it seems to just make me laugh more than actually think or learn. So something in the middle would be One Piece, agreeing with your statement. It really gets me to think and feel for the characters, but at the same time, it's a funny anime. So, I'd have to agree, One Piece is my favorite anime.