Opcache caches the bytecode, and APCu is a simplified version APC, that only caches the userland part (and it's entirely compatible with the old APC, it just doesn't tdo the bytecaching any more). If you still want to cache locally, APCu is the way to go, and I'll be using it myself when it comes to such caching.
For larger, cross-machine caches, I'll also use Memcached.