The best will be flexi endurance stirrups. Use cages with them and you can wear well cushioned trainers/walking boots or whatever else you find comfortable.
I loved my Metalabs, they were a game changer for me. Stopped all knee, ankle and hip pain immediately. They look quite traditional which I really like. Now I’m retired from riding I must stick them on eBay!
It's very personal and it depends on your exact issue, sorry! For some a 90 degree slot for the leather really helps, if it's toroque on the knees that's the problem. If it's a lack of support under the knee to help stabilise it then stirrups will make less difference. If it's a problem caused by the saddle making your thigh unstable then again stirrups may not be the fix.
You could look at stirrups with suspension as a preference to hinges, hinged stirrups take away our proprioception which is already hugely reduced from the feedback we get when standing on the ground.