Some interesting responses so far - my suspicion that the results of this poll would be largely dependent on the voter's opinion of Several Species of Small Furry Animals... has proven more or less correct (i.e. several people who voted for Seamus did so out of dislike for Several Species rather than any particular fondness for Seamus).
I think both of these recordings (not sure you can call Several Species... a song!) are far from the quality of Pink Floyd's best music, neither comes close to songs like If or A Pillow Of Winds, let alone Floyd classics like Comfortably Numb or Time.
On a subjective scale of 0-5 for song quality:
5 - Great
4 - Good
3 - Decent
2 - OK
1 - Bad
0 - Not music!
Seamus scores 2, Several Species scores 0.
On a subjective scale of 0-5 for humour:
5 - Hilarious
4 - Funny
3 - Slightly funny
2 - Barely raise a smile
1 - Not funny
0 - Depressing
I give Seamus 3, and Several Species 5 (on first listen, at least).
I did consider including Alan's Psychedelic Breakfast in this poll, but I thought better of it as I actually think it's a good song musically, especially part 2 (Sunny Side Up) - Gilmour's steel guitar playing is lovely - it blows away these two for sure as far as I'm concerned.