@pirahansiah
I think the Apple M4 will be the best choice for LLM/Machine Learning research. The M1 NPU offers 11 TOPS, the M2 NPU 15.8 TOPS, the M3 NPU 18 TOPS, and the M4 NPU 38 TOPS. While the RTX 4090 offers more TFlops, it is limited to 24 GB DDR5, whereas the M4 Max/Ultra allows you to significantly increase the RAM.