1. If you are considering the performance of the overclocked, then consider the performance of the overclocked R9-280X too. There is no point comparing the stock 280x with an overclocked 760. When comparing both the overclocked 760 as well as the overclocked 280X, then the 280x would win between these two.
2. The 760 has 2GB VRAM v/s the 3GB VRAM on the 280x. And BF4 plays barely below the 2GB RAM mark at 1080p but as son as the VRAM utilization goes more than 2GB, then the graphics card with 2GB RAM start swapping the VRAM and hence there is a performance dip there which of course is not desirable as it can cause dropped frames.
Hence going for the 3GB VRAM makes more sense.
3. The 280x comes with 3 free games from AMD's never settle bundle. You can choose what games you want to select from 8. Wheras in Nvidia bundle, you are going to get the games that they are offering, whether you want to play those games or now.
4. The wider bus provides more memory bandwidth to the 280x. 280x has 384 bit bus which is significantly more than the one in Nvidia 760.
5. Also we also need to make sure that whether his CPU would be able to handle the high end GPUs like 760 and 280x. So, first let him tell that what is his hardware configuration first, so let the OP mention his specs, then would be the best time to suggest any hardware.