Maybe I'm biased towards Roger Waters a bit, but I think Pink Floyd ceased to exist the moment Waters left the band.
AMOLR and Division Bell are IMHO two of their worst albums, yes there are many standout tracks but taken in their entirety they are just lacking. One of the great things about Pink Floyd is that none of their albums sound alike, in great thanks to Waters I believe. All albums made after he left tried too hard to sound like Floyd, which Gilmour and co. were able to do but they lacked the creativity that Waters brought to the table.
Anyways, since we are voting for best song and not album I guess anything under the name Pink Floyd counts.