The most sought after feature is the ability to export ProRes. With MOV and MXF OP1a as supported containers. Progressiv and Interlaced options. With up to 16 mono audio channels for broadcast needs.
With ProRes 444 and above bit depth should support 12bit (atm Voukoder seems to use 10bit only), and alpha channels with ProRes 4444.
And having x264/x265 options would be great too. Currently h264 output from Resolve is ok, but not great and lacks settings and quality when outputting h264 as the end file format.
I think those are the most important features people are looking for.
Personally for me ProRes is by far my number 1 on the wishlist.