Personally, I prefer "short and slim", with emphasis on overview. So, my ideal method has very short lines, contains logically grouped / scoped blocks of statements and doesn't use up much vertical space. Since this results in rather vertically visually long code, I like to turn my 16:9 monitor by 90° :)

Just as long as it should be.

It really depends on what that method is designed to be. Sometimes it is better to keep it longer instead of breaking it in smaller ones to avoid spaghetti code.