What are the best and your favourite software design patterns?

The last days I'm into the clean code, refactoring, SOLID methodology and how to make a good code, but i don't know so much about patterns and have a question.

What are for you the best design patterns or almost the most useful? Thanks for all!

PS: I have in mind to learn more about design patterns and instead I know some patterns, but always is interesting to have a external point of view!