I have assembled a list of the most controversial Wikipedia articles from the data on this page: https://en.wikipedia.org/wiki/Wikipedia:Database_reports/Talk_pages_by_size

There are 66 pages from the main article namespace listed there, and they are, in order of total size of all talk page archives, as follows:

1. Donald Trump
2. Intelligent design
3. Climate change
4. Barack Obama
5. Race and intelligence
6. Jesus
7. United States
8. Catholic Church
9. Homeopathy
10. Circumcision
11. Chiropractic
12. Monty Hall problem
13. Muhammad
14. Gaza War (2008-2009)
15. Evolution
16. Gamergate controversy
17. Abortion
18. Sarah Palin
19. Prem Rawat
20. Christ myth theory
21. World War II
22. India
23. Jehovah's Witnesses
24. Cold fusion
25. Climatic Research Unit email controversy
26. September 11 attacks
27. Atheism
28. Anarchism
29. George W. Bush
30. Falun Gong
31. Armenian Genocide
32. Neuro-linguistic programming
33. Israel
34. Cities and towns during the Syrian civil war
35. Jerusalem
36. Mass killings under communist regimes
37. Transcendental Meditation
38. British Isles
39. Libertarianism
40. Kosovo
41. Christianity
42. Thomas Jefferson
43. International recognition of Kosovo
44. United States and state terrorism
45. United Kingdom
46. Acupuncture
47. Israel and the apartheid analogy
48. Syrian civil war
49. Adolf Hitler
50. COVID-19 pandemic
51. Russo-Georgian War
52. Second Amendment to the United States Constitution
53. Tea Party movement
54. Murder of Meredith Kercher
55. Genesis creation narrative
56. Historicity of Jesus
57. Electronic cigarette
58. List of best-selling music artists
59. Shakespeare authorship question
60. List of sovereign states
61. Taiwan
62. Michael Jackson
63. 0.999...
64. European Union
65. Chronic fatigue syndrome
66. Russian interference in the 2016 United States elections