At this point we consider rustls about as secure or a little more. Ring is a high-quality set of primitives thats basically some carefully ported boringssl code, and both it and rustls have been around for a good while and have plenty of contributors. Tbh we like the lack of old legacy cruft (where most openssl bugs get found) as much as a memory-safe language, ditching all that ancient code we don't need really cuts down attack surface.