Ther are many, many, many which API people should use (DirectX, OpenGL or Glide). I'd say Direct3D wins because it's fast and compatible to all graphics cards. OpenGL, however, has better quality than D3D while D3D supports new technology earlier tahn OpenGL... (Glide is only for Voodoo cards but very fast)

As I said you can't really say one of them is better, but I'd recommend you using D3D. Best -of course- is if your engine supports all 3 rendering APIs and also software emulation

I personally like D3D more and it's a good feeling to use the DirectX package from A-Z (DInput, DPlay, DSound, D3D,...) instead of having an 'external' renderer ...