If you're talking about quality, it would be H.265 otherwise known as HEVC. 

For submission to Stock and other agencies, H.264 is still very safe and much more common.  Laptop computers and NLEs are just starting to be able to play back h265 effectively.

I'd like to accept h265 at some point because it is a higher quality codec, but as of today the market still like h264 and large codecs like prores.

Hope this helps,
Dennis