What processor do I need for motion graphics design?

I am a motion graphics designer (think After Effects animations and Premiere Pro editing). I am looking up upgrade my 21.5 inch late-2013 iMac. She's been good to me, but she's starting to buckle under the strain of motion graphics editing. I am looking to try and "future proof" a 27-inch iMac but I need help selecting a processor.

If I pick the middle model I can get 3.3GHz 6-core 10th-generation Intel Core i5 processor, but I'm given the option to upgrade to 3.6GHz 10-core 10th-generation Intel Core i9 processor. If I pick the higher end model I can get 3.8GHz 8-core 10th-generation Intel Core i7 processor, but can upgrade to 3.6GHz 10-core 10th-generation Intel Core i9 processor.

I honestly have no idea what any of that means. I understand that the better the processor, the better the performance. I understand that the better processors cost more money. But what processor does a motion graphics designer actually NEED before money's just being spent on diminishing returns?