Usually, ubuntu is good option, but I do prefer mint for my Linux users.
For my opinion Gentoo is very good option, but you do have to know how to live in Linux and open source world, should be best performance, if properly tuned.
GPU acceleration is currently not used in OpenDCP as far as I know, so you should not care that much about.
afaik UBUNTU is the only distribution that offers propriety drivers. that's what you are looking for if you need high performance/certain features. but i do not think, openDCP offers GPU acceleration. it solemnly runs on (all of) your CPU cores i think.