I'm trying to do some performance (time) calculations over TLS. I have the data I need for a variety of cipher suites but in order for the calculations to generalize well, I need to know if there is a clear most popular choice for TLS 1.2 cipher suite. Data to back up any answers would be appreciated.
The first web search hit I find is:
This claims that the most widely supported cipher suite among the Alexa top 1m sites is ECDHE-RSA-AES256-GCM-SHA384, supported by 147 985 servers. Raw data and methodology are at the link.
Other links found by a quick search that may have similar data about HTTPS servers:
(This answer will be outdated within a year or two, if not in months.)
If you are trying to decide what cipher suites to configure your HTTPS server to use, based on what browsers you want to support and what software you're running on the server, you should use this tool: https://mozilla.github.io/server-side-tls/ssl-config-generator/
If these don't answer your question, you'll need to be more specific about why the quick web search results aren't what you're looking for.
Beware that AES, GCM, RSA, and ECDH in that cipher suite are likely to be vulnerable to timing side channel attacks if implemented in software!