The only way to encrypt today is authenticated encryption, or "AEAD". ChaCha20-Poly1305 is faster in software than AES-GCM. AES-GCM will be faster than ChaCha20-Poly1305 with AES-NI. Poly1305 is also easier than GCM for library designers to implement safely. AES-GCM is the industry standard.
Use, in order of preference:
- The NaCl/libsodium default