Attitudes towards Spanish dialects- PLEASE RESPOND!!

[ROBINDESBOIS]

I was born in Spain.
They say the best one is the one spoken in Some parts of Castile. Because their diction follows the rules of pronunciation.
Apparently the worst spoken Spanish in Spain could be the region of Murcia, because sometimes it is really difficult to understand them. There are also some places in Andalucia where you have to make an effort to undestand some speakers, but I think it has to do with individuals.
The best Spanish accent is in Northern Spain, Castile and Leon because words are pronounced completely following the rules.
Countries of South America that I understand much better are, Mexico, Colombia, Venezuela, Costa Rica and Argentina.
Sometimes I have problems with Ecuadorians and Bolivians.
I m not taking into account slang which is different in every country, Just the way people pronounce and use sentence structures.