I too have looked forever into sites for guitar tips and lessons. I am a skeptic when it comes to committing to purchasing things on line, but I did yesterday.
I've heard of the sites you mentioned but never got into any of them.
Yesterday I was searching for tips and came across the GT site. I couldnt be happier and I purchased the one year plan here. I havent put the guitar down, except for sleeping, since yesterday at 3pm and here I am back at it again.
I haven't followed any instructors yet except for the beginner tutorials, which I know most of, but felt I wanted to start from the beginning. With that being said, I have learned things that I thought I already knew..
Im in love with a very exciting website.
Marci