Mark Lamarr was a hateful beast on NMTB, I think I only watched it because of the exposure of people in bands and being able to play along, as alternative music wasn't particularly exposed back in those days. I respected Lamarr on The Word, because he seemed very true to himself and his beliefs, and I was bowled over by the fact that he helped write and appeared 15 Stories High, which is amazing, but I found him repellent otherwise.
Amstell was hugely likeable and very funny on the show, I've always found him very likeable (although he dumped a friend of mine he was dating via his radio show, which was mean) and he's got quite a bad reputation with my gay friends, but thats not my business really, his comedic output is charming, so once he left NMTB the show lost its sparkle for me...finally. However, Noel Fielding, as much as I want to dislike him, was a very welcome addition.