GUI is more important I'd say. OSX is uncommon, particularly for mining machines. On the other hand, command line presents a large psychological barrier for many even when simple step-by-step instructions are given. But, yes, there needs to be an OSX binary for CryptoNote soon. The BCN website said they'd be coming but who knows what their time frame is? I hope someone on this forum is working on it.
The best possible outcome is OSX client with GUI lol.
Also, I wonder how Bytecoin daemon will be delivered to OSX. .dmg file or terminal-linux-like-making.
Bytecoin really needs some simplicity atm - the easier - the better.