I have to install both due to dependency (Nginx only support openssl, and luci-app-acme only uses mbedtls)
I wonder what tld module I would use for other things like wpad or openvpn (and no, other end doesn't support wiregurd)
if target matters, it's ramip mt7621 (MIPS)
It's complicated... Depends on your use case - mbedtls is focused on small footprint
Both are equally secure for the most part.