The gap was MUCH larger in the past, but in my tests, oMLX and llama.cpp are now very similar (within 10%) in both prompt processing and generation speed. GGUF ecosystem provides a better selection of quants, in my experience Unsloth ones are excellent.

I thought the main advantage of oMLX is it's less likely to invalidate the KV cache when working with coding agents, which is key when working on a Mac because of the slower prompt processing.