As most companies hold theme park attendance a trade secret, the Themed Entertainment Association (TEA) is the industry standard for public ranking of theme park performance.

The TEA has released their list of the Top 25 Theme Parks in the World for 2017:

Quote Originally Posted by Themed Entertainment Association
# Theme Park % Change 2017 2016
1 MAGIC KINGDOM AT WALT DISNEY WORLD, LAKE BUENA VISTA, FL, U.S. 0.30% 20,450,000 20,395,000
2 DISNEYLAND, ANAHEIM, CA, U.S. 2.00% 18,300,000 17,943,000
3 TOKYO DISNEYLAND, TOKYO, JAPAN 0.40% 16,600,000 16,540,000
4 UNIVERSAL STUDIOS JAPAN, OSAKA, JAPAN 3.00% 14,935,000 14,500,000
5 TOKYO DISNEYSEA, TOKYO, JAPAN 0.30% 13,500,000 13,460,000
6 DISNEY'S ANIMAL KINGDOM AT WALT DISNEY WORLD, LAKE BUENA VISTA, FL, U.S. 15.30% 12,500,000 10,844,000
7 EPCOT AT WALT DISNEY WORLD, LAKE BUENA VISTA, FL 4.20% 12,200,000 11,712,000
8 SHANGHAI DISNEYLAND, SHANGHAI, CHINA 96.40% 11,000,000 5,600,000
9 DISNEY'S HOLLYWOOD STUDIOS AT WALT DISNEY WORLD, LAKE BUENA VISTA, FL, U.S. -0.50% 10,722,000 10,776,000
10 UNIVERSAL STUDIOS AT UNIVERSAL ORLANDO, FL, U.S. 2.00% 10,198,000 9,998,000
11 CHIMELONG OCEAN KINGDOM, HENGQIN, CHINA 15.50% 9,788,000 8,474,000
12 DISNEYLAND PARK AT DISNEYLAND PARIS, MARNE-LA-VALLEE, FRANCE 15.00% 9,660,000 8,400,000
13 DISNEY CALIFORNIA ADVENTURE, ANAHEIM, CA, U.S. 3.00% 9,574,000 9,295,000
14 ISLANDS OF ADVENTURE AT UNIVERSAL ORLANDO, FL, U.S. 2.00% 9,549,000 9,362,000
15 UNIVERSAL STUDIOS HOLLYWOOD, UNIVERSAL CITY, CA, U.S. 12.00% 9,056,000 8,086,000
16 LOTTE WORLD, SEOUL, SOUTH KOREA -17.60% 6,714,000 8,150,000
17 EVERLAND, GYEONGGI-DO, SOUTH KOREA -9.50% 6,310,000 6,970,000
18 HONG KONG DISNEYLAND, HONG KONG SAR 1.60% 6,200,000 6,100,000
19 NAGASHIMA SPA LAND, KUWANA, JAPAN 1.40% 5,930,000 5,850,000
20 OCEAN PARK, HONG KONG SAR -3.30% 5,800,000 5,996,000
21 EUROPA-PARK, RUST, GERMANY 1.80% 5,700,000 5,600,000
22 WALT DISNEY STUDIOS PARK AT DISNEYLAND PARIS, MARNE-LA-VALLEE, FRANCE 4.60% 5,200,000 4,970,000
23 DE EFTELING, KAATSHEUVEL, NETHERLANDS 8.70% 5,180,000 4,764,000
24 TIVOLI GARDENS, COPENHAGEN, DENMARK 0.00% 4,640,000 4,640,000
25 UNIVERSAL STUDIOS SINGAPORE, SINGAPORE 2.90% 4,220,000 4,100,000
Of note this year, Disney's Animal Kingdom and Epcot has switched order for the first time.