I'm afraid it was me who said it - I had ORLANDO PALADINO in mind at the time, I think?  However, I think even Haydn's major supporters have agreed that he had poor librettos foisted on him, over which he had little choice. Luckily there are several amongst his operas which have a wild "fantasy" element that makes good theatre anyhow:  IL MONDO DELLA LUNA ("The World Of The Moon"), and L'ISOLA DISABITATA ("The Desert Island"), for example.

Does anyone know "LA CANTERINA" ("The Opera-Singer") - I've never heard that one?   I read somewhere (in a sleeve-note about Mozart's BASTIEN & BASTIENNE, I think?) that Mozart was indebted to Haydn for the creation of the genre of German-language Singspiels, pantomimes, "Hans-Wurst" slapstick pieces etc...   but I realise I don't actually know any such pieces by Haydn?   In fact "PHILIMON UND BAUCIS" is the only one I know of with a German title...  the title seems to suggest some kind of "pastoral" piece - does anyone know the music?

I hope so too - Haydn's operas are at least as good as many of the "lesser talents" of the era, like Cimarosa, whose works are now being staged quite frequently.  It's a pity he lost interest in writing operas in his later years - I wonder what "mature Haydn" operas might have sounded like?

But I got some very nice Irish songs today in a packet    Thank you very much 

Ooooh, I'm not qualified to compare Mozart with Haydn.  If I'd paid attention in my lectures long ago, perhaps I would have a chance, but I think here we need Ollie or Ron or Richard or Ian.

The only comparison I know between Mozart and Haydn has - oddly enough - got an Irish connection.  It's called "The O'Grady Minuet Test", and it's taught to kids,  as a way of telling Haydn from Mozart.  Here's how it works.  Your job is to tell from a sonata, symphony, cassation etc whether the composer is Haydn or Mozart.  You quietly relax in the first two movements.  Then comes the minuet.  Can you fit the following words to the minuet?  "Are YOU the o'GRA-dy who RUNS this ho-TEL?".  If yes, then Mozart.  If not, then Haydn.  Please collect a Bachelor Of Music Certificate from the chair at the back as you leave.  Next week we tell Berg from Webern with the assistance of some iron filings and a magnet.

eruanto,
I think that in piano sonatas Haydn does have more humour, but in operas Mozart has plenty of humour.
Do you agree?

exactly! that's the reason for "consistently".  

Haydn's humour is more hum intellectual, i think.