What do you want to accomplish? Do you want good implementations of cryptographic primitives, or something else? As a general rule: OpenSSL, BoringSSL if you c

What do you want to accomplish? Do you want good implementations of cryptographic primitives, or something else? As a general rule: OpenSSL, BoringSSL if you can get away with it, don't use NSS or LibreSSL. But that presupposes that using a library like OpenSSL was the right answer to begin with :)