Nvidia and AMD broadly cover the same use cases. Nvidia cards are not intrinsically better to my knowledge, Nvidia simply offers ultra high-performance cards that AMD doesn't.

If you just need nonspecific games to run decently, a card from either brand will do it. If you need to run the most intensive games there are on unbelievable settings, that's when Nvidia should be edging out.

ML dabbling may complicate things. Many (most?) tools are written for CUDA, which is a proprietary Nvidia technology. I think AMD offers a counterpart but I do not have details. You will need to do more research on this.