What is your criteria for a GA?

I know that when I give a GA, ("Good Answer" for you newbies) to a particular post it is because I find that the responder has provided a wealth of effective and real information that can be considered an important part of the 'body of knowledge' for any given subject. This can be schematics, images, links, prose, fact, math, experience, humour, etc.

I may or may not provide a few words with it, as in some threads, I may not want to subscribe automatically by posting, but it may be evident to me that some post is particularly relevant, and other posters have been negligent in recognizing the value of a given post. Therefore, for posterity, I give a GA, based on my comprehension of the subject, and the relative amount of value delivered.

What are some of your thoughts on this?

Chris