These are the same base underneath, so this is not a performance comparison - it is a licensing one. Both put out 8 Nm from the same chassis and score identically on everything except compatibility, where the GT DD Pro pulls ahead purely because it carries the official Sony licence. It was developed with Polyphony Digital specifically for Gran Turismo 7, and that licence is the only reason it exists as a separate product.
So the decision writes itself once you know your platform. If you race on PlayStation, the GT DD Pro is the pick - it is the only officially licensed direct drive base for the console, so nothing else here is even eligible. If you are on PC or Xbox, you are paying $120 for a licence you will never use, and the CSL DD 8 gives you the identical base for less. The GT DD Pro's one knock, a slightly plasticky bundled wheel, is common to the tier and not really about the base.
In short: PlayStation buyers pay the small premium and get in; PC and Xbox buyers save the $120 and buy the CSL DD 8. There is no feel or torque difference to agonise over, because it is the same hardware - the licence is the whole distinction.