What PSU wattage do you have installed?
What will be the main reason for your using your PC?
If it is for Rendering or using Professional type software like Photoshop or a 3D Program, I suggest you go to their Support site and see which GPUs are recommended for running those types of programs.
Choose the one that will run those types of programs the best.
The reason why I mentioned the above because some Professional type programs are optimized for Nvidia and others for AMD GPU cards while other can use either.
If it is just for mainly playing games then either Nvidia or AMD will work. Depending on your Budget and PSU wattage you have installed.