In terms of quality, x264 and x265 are better than hardware solutions, because hardware solution requires money to make larger circuts that implements code the software solution already does (if the encoder section costs under 100USD, they are no match with software encoding), the only advantage is in lossless codecs where the hardware encode runs cooler and faster.
x264 and x65 from ffmpeg are advantageous in double pass encoding. In single pass, you already have software/native encoding in Resolve, which I consider equivalent in speed/performance.
As far as I know only single pass is available in Voukoder yet, for SDK constraints. If you want double pass x264/x265, you may export to DNxHD in Resolve and double-pass with ffmpeg/Handbrake later.
