This comes from Mercer but excluding cities whose metropolitan area is less than 1 million. It's not bad, but cities in the same country tend to be clumped together.
London is at 36, and New York doesn't show up until 38.
1. Vienna, Austria
2. Zürich, Switzerland
3. Vancouver, Canada
4. Munich, Germany
5. Auckland, New Zealand
6. Düsseldorf/Cologne/Bonn, Germany
7. Frankfurt, Germany
8. Copenhagen, Denmark
9. Sydney, Australia
10. Amsterdam, Netherlands
11. Berlin, Germany
12. Toronto, Canada
13. Melbourne, Australia
14. Ottawa, Canada
15. Hamburg, Germany
16. Perth, Australia
17. Montréal, Canada
18. Nuremburg, Germany
19. Stockholm, Sweden
20. Oslo, Norway
21. Singapore, Singapore
22. Stuttgart, Germany
23. Brussels, Belgium
24. Adelaide, Australia
25. Helsinki, Finland
26. Calgary, Canada
27. Dublin, Ireland
28. San Francisco, US
29. Brisbane, Australia
30. Boston, US
31. Lisbon, Portugal
32. Honolulu, US
33. Paris, France
34. Lyon, France
35. Milan, Italy
36. London, UK
37. Barcelona, Spain
38. New York, US
39. Edinburgh, UK
40. Madrid, Spain
41. Seattle, US
42. Glasgow, UK
43. Osaka/Kobe, Japan
44. Tokyo, Japan
45. Birmingham, UK
46. Chicago, US
47. Washington, US
48. Philadelphia, US
49. Yokohama, Japan
50. Rome, Italy
51. Pittsburgh, US
52. Leipzig, Germany
53. Minneapolis, US
54. Nagoya, Japan
55. Dallas/Ft Worth, US
56. Atlanta, US
57. Houston, US
58. Los Angeles, US
59. Miami, US
60. Prague, Czech Republic
61. St. Louis, US
62. Hong Kong
63. Detroit, US
64. Dubai, United Arab Emirates
65. Budapest, Hungary
66. Seoul, South Korea
67. Abu Dhabi, United Arab Emirates
68. Montevideo, Uruguay
69. Warsaw, Poland
70. Taipei, Taiwan
71. Kuala Lumpur, Malaysia
72. Durban, South Africa
73. Athens, Greece
74. Riga, Latvia
75. Buenos Aires, Argentina
76. San Juan, Puerto Rico
77. Santiago, Chile
78. Busan, South Korea
79. Cape Town, South Africa
80. Johannesburg, South Africa
81. Panama City, Panama
82. Zagreb, Croatia
83. Wroclaw, Poland
84. Johor Bahru/Iskandar, Malaysia
85. Taichung, Taiwan
86. Shanghai, China
87. Tel Aviv, Israel
88. Muscat, Oman
89. Brasilia, Brazil
90. San José, Costa Rica
91. Bucharest, Romania
92. Doha, Qata
93. Monterrey, Mexico
94. Tunis, Tunisia
95. Asunción, Paraguay
96. Sofia, Bulgaria
97. Rabat, Morocco
98. Rio de Janeiro, Brazil
99. São Paulo, Brazil
100. Beijing, China