Well the i9 10 core appears to have the processing advantage- and the more memory the better. For graphics and storage I’m now a fan of NOT putting it all into one box (your iMac). One-box solutions are hard to update and costly.
I’ve been editing/doing AE work with my 2018 MacBook Pro i9 6 core / pro vega 20 (in clamshell mode diving 3 external monitors) with an external graphics processing unit (eGPU) connected and external SSD storage. It really screams along and AE & Premiere work great with the eGPU.
So if you can swing it, sure get the maxed out iMac- but if you want to add more graphics processing power- consider using a thunderbolt-connected eGPU.