A Canticle for Leibowitz by Walter M Miller - IMO, nothing in science fiction comes close to being as emotional as this (though it is occasionally humorous, unlike Pratchett, it's role is in alleviating comedy)
Guy Gavriel Kay's the Lions of Al-Rassan
If you're looking for some more literary fantasy/science fiction:
Both Gloriana by Michael Moorcock and the Gormenghast trilogy by Mervyn Peake have some pretty emotional bits - they aren't easy going, but definitely worth reading. Also, I found the Trial by Franz Kafka to be pretty emotional at the end. But the hardest out of these three.
In epic fantasy, it's a little easier, but you need to read the whole series:
1) Steven Erikson's Malazan book of the Fallen (admittedly, the first book is nothing like as emotional as the latter books - you may want to start with Deadhouse Gates, the second book, then read the first book - you'd probably enjoy it more that way). Incomplete series, but plotlines tie up at the end of each novel - a series, not a multipart novel
2) George RR Martin's A Song of Ice and Fire - has some very emotional parts in, but again is incomplete, and the books can't standalone at all.
3) R Scott Bakker's Prince of Nothing