Okay but the show did not succeed because John was the main Green Lantern instead of Hal. When they started making animated Justice League movies they started using Hal and they still made money. Neither of them was the reason a Justice League series or movie was successful. It had more going for it than them. He had some good stuff in that show definitley. But this idea that it proved he was successful (especially if the contrast is Hal wasn't successful) is not accurate. They could taken out all the Green Lantern's and made Aquaman a main member and it wouldn't have made much of a difference.
I like all the Green Lanterns, I'd rather it be an ensemble. I think you can do interesting things with all of them. The show would be worse if it was limited to just one, but realistically if it was, it should be either Hal or Kyle because the stories were designed around them being the main Green Lantern and Guy and John were more placeholders or guys who could sub in as members of different teams despite having a few pretty good stories. I didn't see the need to limit it. If you're going to CGI Kilowag or Sinestro there is no reason you can't hire a few guys to play the other Green Lanterns and you can't have an episode or arc that focuses more on one than the other.
My opinion it should be like Star Trek where you have have Hal (Kirk), John (Spock), Kyle (McCoy). That way they can each have their own strengths, you can have different episodes featuring each one, and none of them has to be perfect because the other character has a skill set to compliment them.