There’s an IETF draft for version 6 of the SOCKS protocol: https://tools.ietf.org/html/draft-olteanu-intarea-socks-6-02
They added TLS encryption and removed a bunch of round trips from connection setup. This addresses the main issues Shadowsocks addressed, but in a more robust way.
It seems to be strictly better at first. It would be great if people reviewed and commented on the email list.
The major missing part is that it does not add encryption to UDP proxying (why???). If they had that, then you would be able to get the Shadowsocks performance with an Internet standard that wouldn’t give away you are a proxy.