Man...tough call.
I've liked both Hal and Kyle over the years. Their GL comics were both among the ealiest superheroes I ever read and collected (in fact, I used to have more GL comics than any other character, until Batman and The Flash caught up). The days of the Green lantern Corps and the Guardians were, in my opinion, sci-fi at it's greatest. It was one of the most epic sci-fi fantasy stories ever created. I didn't really care too much for "Emerald Dawn" - I thought it was an interesting idea, but the execution seemed flawed. I'm also not too sure I liked what they did with the Guardians and the purprose of the GLC (preserving order instead of fighting evil.) But I did like the Hal adventures, as long as the writing was good, as it often was.
As for Kyle, like I said, he was one of my firsts, so what may have been old hat for some fans was fresh and new to me, so I enjoyed watching him find his place. If I'd been more of a comic reader before discovering Kyle, who knows what I would have thought of him? But he's definitely come a long way, and except for when Judd Winick was writing, the Kyle Rayner GREEN LATERN comics were my favorite title (Ben Raab is slowly winning me back).
I also really liked the idea of Hal becoming Parallax. If you think about it, it seems appropriate, because it follows the theme of "the greatest GL becoms evil, and the new guy has to take him down." When Hal was a rookie in training, Sinestro was the greatest of the GLs, until he went to far and became a dictator, and Hal was the one to take him down. Then Hal became the greatest, and then he went insane, and now the new rookie, Kyle, has to take him down. Rob's right - Parallax would have made the perfect arch-enemy for Kyle, following in the footsteps of the Hal-Sinestro feud.
That, and Hal was actually kind of interesting as Parallax - he really does want to "set things right," and he's not really evil. When you can see things from his point of view, he's actually a very tragic character. You almost feel sorry for him, the way you might feel sorry for Magneto in certain stories.
