Well, You should have said : D3d vs OpenGL. Since Direct X has other non 3D gfx related items like Direct sound, Direct play and Direct music.
For me I prefer D3D over OpenGL since it requires less coding experience and still gives nice results compred to OpenGL. But if you really let me choose the perfect API it would be Glide which made it's job perfectly and gave higher frame rates for voodoo cards. And when it was first introduced neither D3D nor OpenGL could compete it.
Just my personal opinion though ^_^ .
For me I prefer D3D over OpenGL since it requires less coding experience and still gives nice results compred to OpenGL. But if you really let me choose the perfect API it would be Glide which made it's job perfectly and gave higher frame rates for voodoo cards. And when it was first introduced neither D3D nor OpenGL could compete it.
Just my personal opinion though ^_^ .