Interesting, because I thought the quieter, low stuff Eric Clayton sang for Day 17 was actually his best performance on the album. He seemed to tone it down compared to what he did on the rest of the record, and that helped.
Of the singers on the album, I'm hard pressed to say whether I like Arjen Lucassen, Mikael Akerfeldt, or Devon Graves the best. All three turned in great performances on this album. As for Arjen himself, I think he may underrate his own voice. I'll always want him to continue with the guest vocalists, but he really has a neat, unique-sounding voice and he holds a tune well. And Devon Graves...wow. All I can say is eventually I'll be checking out Dead Soul Tribe thanks to what he did. Especially "Pain". I do think Mikael may have been a bit underutilized. What he did do was great, though. "YOUR WAYS CANNOT BE JUSTIFIED!" Somehow this actually looks like an Opeth lyric.
As for "Loser", I actually think it's Devin Townsend who messes that one up as opposed to Mike Baker. I think Baker's pretty funny as the father, in a way that really reminds me of "The Trial" by Pink Floyd. Townsend's scream is just way too high-pitched and it goes on for too long for me. (Yet I can listen to an entire album of someone growling as opposed to screaming. Go figure.)
I STILL can't name a favorite song, though, because there are so many excellent ones vying for attention. Maybe sometime I'll have to try naming one per disc, but I think even that will be tough.