Here are the top 46 Tumblr sites based on traffic and engagement:

1. fuckyeah-nerdery.tumblr.com
2. prnkstr.tumblr.com
3. georgetakei.tumblr.com
4. mrsstilinski24.tumblr.com
5. beerbongsandbros.tumblr.com
6. mistergoodlife.tumblr.com
7. scificheerleader.tumblr.com
8. emergencykittens.tumblr.com
9. lissadawn.tumblr.com
10. gothiccharmschool.tumblr.com
11. wuggle.tumblr.com
12. feminismandmedia.tumblr.com
13. tumblrology.tumblr.com
14. thelitbeast.tumblr.com
15. mydarlingharry.tumblr.com
16. throwatom.tumblr.com
17. shiarasnow.tumblr.com
18. roflcat.tumblr.com
19. nerdygeekyhipster.tumblr.com
20. chelisawesome.tumblr.com
21. aniving.tumblr.com
22. socially-awkward-bitch.tumblr.com
23. 1msweet.tumblr.com
24. foodrepublic.tumblr.com
25. thehollowbastion.tumblr.com
26. the-last-teabender.tumblr.com
27. monstertruckninja.tumblr.com
28. oddmentosity.tumblr.com
29. wondertwinstudies.tumblr.com
30. emckeigan.tumblr.com
31. nolanmyers.tumblr.com
32. msjadewhitaker.tumblr.com
33. beardsoftumblr.tumblr.com
34. freetheunicorns.tumblr.com
35. thepaperhaunts.tumblr.com
36. accioproductions.tumblr.com
37. milesofgifs.tumblr.com
38. oldhollywood-glamour.tumblr.com
39. ethereal-souls.tumblr.com
40. susanoo.tumblr.com
41. adventuretimepedia.tumblr.com
42. artweaver.tumblr.com
43. breadedcats.tumblr.com
44. bookshelfporn.tumblr.com
45. infiniterick.tumblr.com
46. geeksideoftheforce.tumblr