Haley underrated? I think she's the most beloved character on the show according to most fans. She was my favorite aswell alongside Brooke, closely followed by Peyton. I loved the show, and will always love the show but I was never a fan of the boys on the show. They were kind of cute, but that was about it. And that had nothing to do with romance. Sure, in Lucas' case it didn't help that he cheated on Brooke multiple times, but it isn't the prime reason I dislike him. I liked Nathan a bit more, but that was mainly because I liked his relationship with Haley. The only thing I kind of liked about Lucas was the connection he had with Karen. And at times I liked him with Brooke and Peyton. But that was quite rare. Imo it didn't help that their portrayers ( James & Chad ) weren't the strongest actors on the show. The girls on the show were so much better in my opinion.
As to who of them has had the most drama...well, they both got their drama. And they both didn't exactly handle it right a couple of times. But the difference is ; Nathan learned from his mistakes. Lucas' ''mistakes'' had a lot to do with romance and it took years before he finally went for Peyton all the way. No love triangles, etc. Nathan made his mistakes ( gambling, that accident and his depression after S5 premiere ), but he fought and survived. And he never fell that hard again.