Finaly the GPU (Asic,fixed,dynamic function) compare
I guess you will take Mainconcepts GPU ENcoder and Elemental's also into account, though i guess Arcsoft with their own GPU Encoder (Research they had 3 different Encoder implemented 1 was entirely Cuda based though bad quality most probably Mobile optimized just for pure speed, The other was the Pure NVCuvenc (Nvidia implementation) and then they had another one based on X264 implemented with partly GPU support) isn't on the list yet you should ask them if they want to participate