Apart from the overtly humorous pieces (A Musical Joke) I notice no humour in his compositions. Wit, yes, in the way he surprises by doing the unexpected (a socondary theme in the minor, for example).
I'm not sure I agree to that. Depends on one's sense of humor, probably.
By humour I do not mean the braying of asses (the sort of joke R. Strauss is apt to make - Look at his Burleske, where, to my ears at least, the piano imitates a horse neighing). On reflection I might agree with you: the Rondo of Sonata K 545 (I hope I have the number right) has its humour. And the Piano Concerto No. 9; Knowing that in Paris the audience expected a long orchestral introduction what does Mozart do? He has the piano come in at the very start. This is his first great piano concerto. Not for this joke, but for the lovely second movement.
Haydn always has a joke to offer, such as a lyric melody played by the double-bass.
I don't know nearly enough of and about Haydn but from what I heard/read it would seem that he is the more quirky and humorous of the two. Does that make him the better composer ? I am not sure. If we need to compare the two at at all, that is. IMHO, humor in music is overrated. Personally I am a bit allergic to composers (well, people in general) who desire to be funny all the time. Goes with my morose character I guess
People trying to be funny are usually anything but. The funniest ones are the ones who are so by nature. Is Haydn the better composer? Maybe if one examines the symphonies, but not if one examines the concerti. I have never really bothered about this, really. I enjoy both and both in their individual fields.
But much of the best music is not particularly jocular. Think of Brahms, Bach, Rachmaninov, Chopin, Mahler, Tchaikovsky .... Given the choice I'd pick a serious work every time.
Mahler is not always serious. Indeed, at times his songs are humorous; one of them includes... the braying of an ass! The Scherzo of his 1st symphony is almost ridiculous. Brahms has his Academic Festival Overture, Bach has the Coffee Cantata...
Add to that that Mozart's best music is not in his sonatas or symphonies, but in his concerti. It is in the latter that his genius shines through. Out of his 19 sonatas how many are really rewarding to play? I would say 4 or 5.
Did you try them all ?
I have not played them all, but I have certainly listened to them. I find the earlier ones (in the K 200s) a bit long-winded. Some of the ones in the K 300s are good. The one in Bb I find particularly attractive and will even say it is a masterpiece. The 3rd movement has all the atributes of a movement from a concerto but without the orchestra.