The reason for dropping Mac is that the majority of the last year of Poser development has been wasted trying to keep up with what ever Apple broke with the previous OS update. The most recent one is where we reached our breaking point. With OS 15.1 Apple broke OpenGL. OpenGL is how Poser previews the scene. Apple broke OpenGL to the point we had to disable the preview of shadows on Mac. They're trying to force us to move to their completely different, and 100% incompatible preview solution. Apple continues to widen divide between PC and Mac. It's now so big that it's not practical to bridge that divide. Especially when we know the next update from Apple will wreck that effort, making the divide even greater.

To the actual question, The best solution is always a custom built but if you're new to PC that a real stretch. Many of the brand names you know from years of advertisements have outlived their usefulness. (Looking at you Dell). First the biggest deal is the GPU

You definitely want Nvidia because their support of Optix is unparalleled. It can be 40 times faster than a CPU render TIMES. not percent.

Your need to focus on the GPU's dedicated memory. When Poser is rendering on GPU the entire scene and all the textures need to fit in the GPU memory all at once. A GPU with 8GB of dedicated memory should be the minimum. 12GB will be able to handle most any thing you throw at it. Something Like and RTX 4070 will definitely do the job without breaking the bank.

For CPU choice clock speed is more important than lots of cores for Poser. For many operations Poser can't take advantage of multiple cores. Then it's just the base speed of the processor that matters. Something like an Intel i7-13700F.

For main memory no less than 32 GB. 64GB would be ideal. It needs to match the requirements for the chosen CPU. For the mentioned CPU above the memory type is DDR5 5600.

Take those specs to a local computer shop. Any respectable nerd with a screwdriver can build a better PC than the big brands. And, probably for less.