It is especially crazy to omit Monteverdi, who operates right on the edge between the Renaissance and the modern. He didn't invent opera, but he wrote operas that are in a class with Mozart's; he wrote great secular works and great sacred works.
A. C. Douglas predictably disagreed with this in the comments, saying "Not on this planet." Today, he's got a blog posting up about what I said. For reasons that escape me, he's not identifying me or linking to this blog. It's not as if I'm ashamed of this opinion, and surely he is not, though he claims "charity." (Uh, what?) Besides, there's this company called Google, and if you're reading this blog, I presume you know how to do a web search.
I figured something like this would happen, and believe me, I am prepared to defend what I said, and will, in just a minute. I'm going to leave it to John Marcher to deal with the Hendrix/Beethoven issue; he's fully able to defend himself, should he so choose.
First, let's get something out of the way. My comment above should be read thusly:
It is especially crazy to omit Monteverdi from consideration for inclusion in the top ten, owing to his having lived before Tommasini's arbitrary cutoff era of the late Baroque.
It's just as crazy as it would be to omit Wagner from consideration.
Now that that's out of the way, let's get to what really galled ACD, which is my assertion that Monteverdi's operas are in a class with Mozart's. You should bear in mind that, like many reasonably sane people, I regard Nozze di Figaro as, probably, the most perfectly put-together opera in the repertory. It's an amazing clockwork of great music and a complex plot that somehow does get worked out in the end. It's a comic opera, and there's plenty that's funny in it, but there's also the underlying edge provided by our knowledge of the Count's character and what is likely to happen in his marriage. Then there are the class and sexual politics of the opera, which come out more subtly than in the Beaumarchais play from which the libretto is drawn, but which still drive a great deal of the plot.
Two operas that I'd consider to be in a class with Nozze are Verdi's Fallstaff and Monteverdi's L'Incoronazione di Poppea, for somewhat different reasons. Falstaff is worked out something like Nozze in that it is fast-paced, brilliantly scored, fantastically structured, very much driven by both character and plot. It's the summit of 19th century Italian opera; verismo, and especially Puccini's operas, would not be possible without it.
As to Poppeai, as I said in the comments to my original posting, ACD very likely hasn't had the opportunity to see it in close proximity with Nozze. I have, at San Francisco Opera in the late 1990s, both with superb casts. Bryn Terfel, Solveig Kringleborn, Angelika Kirschlager, Bo Skovhus in Nozze, and an even more amazing group of singers in Poppea; Lorraine Hunt Lieberson, David Daniels, Robert Lloyd, Mel Ulrich, Roxandra Dunose, Barry Banks, John Relyea, Norman Shankle...well, it was something. I had to see Poppea twice, and I dragged my slightly reluctant partner to it, too. She thanked me, you bet: the opera got a stunningly great production and performances, the kind that stay in memory forever. It was also the only time I saw the late lamented LHL. She was unforgettable.
Here's why I rank Poppea up there: the music is great and the opera is put together with the same level of genius and finish as Nozze. The plot is even more complex. We have Nero's relationship with the courtesan Poppea and the breakup of his marriage to Ottavia, who is sent into exile. We have Nero's relationship with his teacher, the great philosopher Seneca, a serious and important relationship. We have his friendship with the poet Lucano. We have the relationships between Ottavia and Poppea and their respective nurses; one of these is a comic drag role, amazingly, lending an astonishingly (and anachronistically) modern touch to the opera. We have the loving sacrifices of Drusilla and Ottone, who flee when Ottone is exiled. We have frolicking and innocent youngsters in love, too.
We have the whole political world of Rome and its astonishing corruption, exemplified both by Nero's desire to discard Ottavia for Poppea and in his willingness to send his beloved teacher Seneca to his death in order to preserve his power as Emperor.
So besides the grand political workings-out, which are comparable, perhaps, to Don Carlo and Simon Boccanegra, we have just about every variety of human love, all wrapped up in magnificent music, music that's passionate or austere by turns.
Needless to say, but I'll say it anyway, the fact that I think Poppea is as great as Nozze has absolutely nothing to do with why classical music is trouble. Think about it for a minute: what are the consequences of that opinion? Why, I might encourage people to go see both operas.