A GTX750 is quite underpowered for OR playing. For a fluid experience you'll have to go for something more powerful.
Regarding ATI(AMD) vs nVidia tbqh I've had cards from both manufacturers (and sis, intel, Matrox, ...) and never had much issues with drivers, although I always had a single card. AFAIK ED had issues with older (non GCN) ATI cards.
OR requirements should be similar to passive 3D, so the card RAM should be a concern.
Regarding ATI(AMD) vs nVidia tbqh I've had cards from both manufacturers (and sis, intel, Matrox, ...) and never had much issues with drivers, although I always had a single card. AFAIK ED had issues with older (non GCN) ATI cards.
OR requirements should be similar to passive 3D, so the card RAM should be a concern.