I dunno ... you can make a lot of different cases.
BB85 has a lot of really strong vocals. Some weak tunes, though. Not great work from BW.
KTSA has lots of BW/ML collabs, but BW is nowhere to be heard. And things are pretty bad otherwise.
LA has great work from Carl and Dennis, but the disco and Mike and Al tunes drag things way down.
Love You is kind of a BW solo record and features precious little harmony.
15BO, well, let's not even go there.
Holland is strong throughout, to me, but some hate the Flame tracks.
Carl and the Passions is generally so-so, but has some excellent BW tunes.
So then we come to Surf's Up, which is legitimately great.
So you could make a decent "best since" case for nearly any of these albums. It all comes down to personal preference. I say best group album since Holland, but I think you could make a case for Love You, too. But it also clearly has antecedents in BW85 ... tough.
Great analysis Wirestone....I think for my money it would be since Surf's Up tho....Brian's suite has the same emotional impact as 'Til I Die...something Holland didn't do for me...although it's a very good group effort! Love You is brilliantly quirky...but almost unfinished sounding...