Most of the parallels I've drawn between the two are between the themes and character development: dealing with only one student or so each episode, by the end of which the student's confidence has been gained, and finally the fellow teachers and head teacher- the principal is the cool one on the staff and on the protagonist's side.
I found GTO more exciting and less cheezy than Gokusen in general; but when I watch dramas like this, I can't help but expect some cheese. Perhaps the acting and writing for GTO was just better, and since I saw that first, I couldn't help but feel that Gokusen was just trying to capitalize on the emotions GTO had successfully evoked. The fact that there is a second season of Gokusen (after the main plot issue has been resolved) kind of drove that home for me.
I did watch some of the anime for both shows, and found them better than the live action in some respects. I can only imagine the manga would focus more on Yankumi's trials and tribulations, leading her kind of double life, being from a gangster family, hold a respectable vocation, and have a detective for a love interest.
I've only seen one episode of Dragon Sakura, but it seemed alright; perhaps it's because I find Abe Hiroshi to be a better actor than Nakama Yukie... Can't really speak for the plotline though.