The books I recommend are marked with an asterisk.
1. The Color of Magic
2. The Light Fantastic
3. Sourcery
4. Mort*
5. Equal Rites
6. Wyrd Sisters*
7. Pyramids
8. Guards! Guards!*
9. Faust Eric
10. Moving Pictures
11. Reaper Man
12. Witches Abroad*
13. Small Gods*
14. Lords and Ladies
15. Men at Arms
16. Soul Music
17. Feet of Clay*
18. Interesting Times*
19. Maskerade*
20. Hogfather
21. Jingo*
22. The Last Continent
23. Carpe Jugulum*
24. The Fifth Elephant*
25. The Truth*
26. Thief of Time*
27. Night Watch
28. Monstrous Regiment
29. Going Postal*
30. Thud*
31. Making Money
32. Unseen Academicals
33. Snuff*
34. Raising Steam*
These are the best ones (those rated 5/5 or 4/5):
4. Mort
6. Wyrd Sisters
8. Guards! Guards!
12. Witches Abroad
13. Small Gods
17. Feet of Clay
18. Interesting Times
19. Maskerade
21. Jingo
23. Carpe Jugulum
24. The Fifth Elephant
25. The Truth
26. Thief of Time
29. Going Postal
30. Thud
31. Making Money
32. Unseen Academicals
33. Snuff
34. Raising Steam
The City Watch sequence
8. Guards! Guards!
15. Men at Arms
17. Feet of Clay
21. Jingo
24. The Fifth Elephant
27. Night Watch
30. Thud
33. Snuff
The Witches sequence
5. Equal Rites
6. Wyrd Sisters
12. Witches Abroad
19. Maskerade
14. Lords and Ladies
23. Carpe Jugulum
The Death sequence
4. Mort
11. Reaper Man
16. Soul Music
20. Hogfather
26. Thief of Time
The Rincewind sequence
1. The Color of Magic
2. The Light Fantastic
3. Sourcery
9. Faust Eric
18. Interesting Times
22. The Last Continent
32. Unseen Academicals
Miscellaneous
7. Pyramids
10. Moving Pictures
13. Small Gods
25. The Truth
28. Monstrous Regiment
29. Going Postal
31. Making Money
34. Raising Steam
25. The Truth (the best standalone, and a good introduction to the series)
26. Thief of Time (the single best Discworld novel; not a good introduction to the series)
30. Thud (first read the other City Watch books in order, or at least the top few of them)
4. Mort
6. Wyrd Sisters
8. Guards! Guards!
12. Witches Abroad
13. Small Gods
17. Feet of Clay
18. Interesting Times
19. Maskerade
21. Jingo
34. Carpe Jugulum
24. The Fifth Elephant
20. Going Postal
31. Making Money
32. Unseen Academicals
33. Snuff
34. Raising Steam
Dig deeper if you find yourself becoming a dedicated fan of the series. These are the books that are noticeably flawed, but still have some good points:
2. The Light Fantastic
5. Equal Rites
9. Faust Eric
10. Moving Pictures
11. Reaper Man
14. Lords and Ladies
15. Men at Arms
16. Soul Music
27. Night Watch
28. Monstrous Regiment
These are for hard-core fans who want to read every story, for the sake of completeness. They are the least satisfying.
1. The Colour of Magic
3. Sourcery
7. Pyramids
20. Hogfather
22. The Last Continent
Ann Arbor and Saginaw, Michigan
2007-2011, Updated May 2016