CCM, GCM and OCB2 are all authenticated encryption modes, CBS and CTR are unauthenticated encryption modes.
SJCL is high-level library and it promotes to use most secure authenticated encryption modes, WebCrypto instead is low-level library and provides low-level primitives which you can use to for authenticated encryption.
ATM WebCrypto mention only one authenticated encryption mode GCM, that also support SJCL AFAIK. So from the portability point of view is better to use AES-128 in GCM mode as default symmetric encryption method IMO.
Please note, WebCrypto API isn’t finished yet and list of supported algorithms may change in nearest 2 month.