In response to Anthony Tommasini's list of the ten greatest composers of all time, Michael Zwiebach of San Francisco Classical Voice has posted a list of the ten most underrated composers of all time. I think it's an excellent idea, and I applaud the willingness to present an alternative history, but I sense a paradox at work here: it seems to me that to be excluded from such a list gives anyone greater claim to inclusion. By definition, an unjustly neglected composer who isn't mentioned would be more unjustly neglected than a composer who is.
A corollary to the paradox states that a definitive list of the most obscure x can never be compiled.
That said, my nomination for most underrated composer of the last century would have to be Carl Nielsen, who didn't make Zwiebach's list (and hence is therefore even more deserving). CN is the equal of Sibelius, imho, but he doesn't get played nearly as often, and when he is, the critics are generally no more than respectful, and often not even that. They seem to feel that one Nordic composer should be enough for anyone. Pity: his symphonies are truly extraordinary.
I was happy to see that Lisa Hirsch agrees he should have been included.