I took a look at the top 500 scores on rogueleague. Didn't count losses and tried to avoid counting save-scummed characters multiple times. Here are the results:
Races
Code:
1. Dark Elf 71
2. Human 66
3. Dwarf 63
4. Gnome 48
5. Mist elf 43
6. Ratling 37
7. Hurthling 35
8. Gray Elf 31
8. High Elf 31
10. Drakeling 24
11. Troll 18
12. Orc 13
Dark Elf tops the list, most likely due to the allure of the skillset. Drakeling places surprisingly low, given that it was traditionally considered the "best race"; perhaps IQD has reduced their appeal. Orc lands even lower than troll, with Find Weakness evidently not being enough to counteract their mayfly-like lifespan.
Classes
Code:
1. Wizard 73
2. Monk 44
3. Paladin 40
4. Archer 38
5. Mindcrafter 37
6. Assassin 27
7. Duelist 24
8. Barbarian 23
8. Beastfighter 23
10. Fighter 22
11. Bard 18
12. Priest 14
13. Thief 13
14. Elementalist 12
14. Healer 12
16. Merchant 11
17. Druid 10
17. Necromancer 10
17. Ranger 10
20. Chaos Knight 9
21. Farmer 7
22. Weaponsmith 3
Wizard at #1 as is to be expected, however the other full casters enjoy little popularity. The complexity of smithing seems to be quite discouraging, which is a shame as Weaponsmith is a nice class even if you don't partake.
Top 20 Combos
Code:
1. Dwarf Paladin 16
2. Gray Elf Wizard 15
3. Dark Elf Archer 13
3. Gnome Wizard 13
5. Dark Elf Wizard 11
5. High Elf Archer 11
5. Human Wizard 11
8. Human Mindcrafter 10
8. Human Monk 10
8. Mist Elf Wizard 10
11. Gnome Monk 9
12. Dark Elf Paladin 8
13. Dark Elf Beastfighter 7
13. Hurthling Archer 7
13. Ratling Assassin 7
14. Dwarf Duelist 6
14. Dwarf Mindcrafter 6
14. Ratling Fighter 6
14. Ratling Monk 6
14. Troll Healer 6
Ridiculous PV dwarf beats out even the classic Gray Elf Wizard. The often-recommended Gnome Elementalist was not even close to making this list. Among the races, only Drakeling and Orc fail to make appearances here. Orc is unpopular in general, but Drakeling seems to be lacking an iconic combo, with an even split in popularity between Archer, Monk, and Paladin.