I hadn't seen it either.
I love how Spike still is on lists and wins in polls after all these year.
James Marsters thought the reason it was easier for Spike to move forward was because he’s not as deep as Angel, but Joss said otherwise…
Joss Whedon:
"Well, he’s a different guy than Angel. Hopefully he’s a different guy because otherwise Angel’s going to be really boring. I think Spike was actually a lot closer to human. Angel was at full-tilt evil, that just got clothes lined by those Gypsies and spent 100 years going, "Ah yah aha hah," trying to figure it out — what it was he had to do. Spike actually went in search for a soul while he had none, so I think he was much more evolved then Angel, personally. I think that’s why it was easier for him to make the transition."