Lack of IPv6 support is what keeps us off GCP or AWS, HTTP fronting is great, but when it comes to realtime interactive streams to mobile devices, the ability to save significant latency and avoid the hot mess of CGNAT is invaluble.
I find it a bit ironic that the mobile and web side of the house are pushing very heavily for IPv6 adoption and yet they expect their cloud customers not to need it.
We're on OVH for most things that aren't latency sensitive. For things where every millisecond counts for quality, we either find a 2nd tier cloud provider with decent peering to most of our end users in that area, or less common colo or rent a server (some areas just don't have 2nd tier cloud providers).
IPv6 is not a first-class protocol on AWS, but it is absolutely doable for most scenarios. It still requires having something of a dual-stack network in place (you definitely can't have a v6 only network of anything meaningful).
