The best replacement for dx11 is dx10.

The best alternatives to dx11 are rated as following:
★★★★★  dx10
★★★  x41
★★★  opengl
★★  dx9
★★  dx12
★★  dx9 wow
★★  mantle
★★  x11
★  dx11.2
★  dx9 performance
★  x31
★  dpx21
★  11.1
★  dx7
★  dx9 far cry 3
★  ax720
★  px21
★  dx10.1
  ax 720
  ax pro
  open gl
  tritton ax720
  dx 10

Your alternative for dx11 is not listed? Suggest!
Speaking about dx11, one probably shouldn't forget about dx9.

Other search terms related to dx11 and their ratings are:
★★★★★ dx9
You have in mind a companion for dx11 and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of dx11 in all years. Click on graph for more.
dx11
dx10
x41