I liked Spike better in early Buffy (Season 2 and 4) and then season 5 of Angel. Even though he had a soul in season 5 of Angel, he wasn't Mr.brood-all-the-time or a cheap Angel rip-off like he was on Buffy. His past sins didn't seem to bother him that much, which I liked. He was almost his Season 2-self. Its like he just didn't care about his past sins, which makes sense. Not everyone is going to respond to guilt in the same way or even necessarily feel guilt. I thought it was perfect that Spike showed basically no signs of remorse in season 5 of Angel and even continued to act morally gray without showing any signs of caring about that. It shows all the difference between Angel and Spike. While Angel is willing to accept that Angelus was part of him and he is responsible for his sins, it seems to fit the cowardly nature of Spike that he would justify it as "well, it was just the monster, not me" and be absolutely fine with what he did as opposed to trying to atone.