It isn't, or it is - it all depends on what you want to do. If you give us more information on your goals this will be easier to answer. Otherwise it will turn into a thread full of biased opinions and we will have to lock it :-)
These things nobody can argue with though:
If you want to run on xbox or xbox 360 (commercial game or XNA) then DirectX is your only choice
If you want to run on Mac or Linux then Open GL is your only choice
If you want to run on other consoles.... well I don't know the answer but DirectX isn't a choice
For what you want to do either will work for you. This forum is for DirectX so if you need help with OpenGL you will need to find a similar forum - try here http://www.opengl.org/
Asking which is best is like asking people if Coke or Pepsi is best - they both are good drinks but people will argue forever about the answer.
Dear I Am Asking You As En Expert To Help Me, Cause I Dont Know The 2 Languages.
I Am Sure That DirectX Is The Best Cause It Is Developed And Supported By Microsoft.
Then lets hope someone else chimes in because my OpenGL knowledge is not sufficient. Without much more specific knowledge about what you want to write this is tough. From what you psted in the other thread I would say there is no obvious choice.
I asked a little bit same like question months ago.. :)
http://forums.microsoft.com/MSDN/ShowPost.aspx?PostID=185050&SiteID=1
Hassan Ayoub wrote:
Why DirectX Is Better Than Open GL?
This typically devolves intro a "troll" conversation, so let me nip it here:Asking this kind of question on a Microsoft-hosted forum probably won't get you the answers you want (or need). Andy "Zman" Dunn's response was the most-accurate, actually. However, if you want to read about similar conversations (and believe me, this question is asked OFTEN -- just do a search), I recommend visiting www.gamedev.net and discussing it in their general forums.