I observed that the Android Platform has been used in many of the best mobile phones .Eleven out of top 20 mobile phones use Android Platform, this shows growing clout of Android in Smart Phone Platforms. Apple's iOS , BlackBerry's Phone OS and Windows 7 are used in 2 phones each. Samsung's Bada has been used in one phone, similar is the case with Nokia's Symbian and Nokia's Maemo Platforms.The dominance of Android Platform based phones is strong among top 5 phones also this can be understood by the fact that best 4 phones in top 5 are based on Android and 1 of them is based on iOS.
If we see among Original Equipment Manufacturers HTC is leading with 6 mobile phones among top 20 , Samsung coming 2nd with 4 mobiles, Apple, BlackBerry and Nokia stand 3rd with 2 mobile phones each and LG , Motorola, Sony Ericson having one each. Apple and Samsung have one phone each among top 5 , where as HTC has three phones among top 5.
The list of top 20 mobiles phones in the world is given below.For details regarding these phones one can refer the link
http://www.techradar.com/news/phone-and-communications/mobile-phones/20-best-mobile-phones-in-the-world-today-645440
20. Apple iPhone 3GS - iOS Platform

19. Nokia N900 - Linux Based Maemo Platform

18. Samsung Wave - Bada Platform

17. HTC Legend - Android Platform

16. BlackBerry Bold 9780 - BlackBerry Platform

15. Samsung Galaxy Europa - Android Platform

14. BlackBerry Torch - BlackBerry Platform

13. HTC WildFire - Android Platform

12. HTC HD7 - Windows 7 Platform

11. Motorola Milestone 2 - Android Platform

10. LG Optimus 7 - Windows 7

9. Orange San Francisco - Android Platform

8. Sony Ericson Xperia X10 Mini - Android Platform

7. Nokia N8 - Symbian Platform

6. HTC Desire Z - Android Platform

5. Google Nexus S by Samsung - Android Platform

4. Samsung Galaxy S - Android Platform

3. HTC Desire HD - Android Platform

2. Apple iPhone 4 - iOS Platform

1. HTC Desire - Android Platform
