IMO you're suffering sort of a first world problem. A GTX780 should give you a solid 60 FPS on a 1080p screen with the default settings or better most of the time. After all, it's still in top twenty of all gaming cards, current and past.
Of course, as has been said, if you're using a multi-monitor setup or 4k or VR you might need a more powerful and modern card.
As for the manufacturers, there's a couple of gaming card designer manufacturers, namely Nvidia and AMD. They design and build the reference cards, which then can be copied and modified within the design. Then there's the big manufacturers who build the cards under their own brands. That serves both risk management and ability to fill large demand bursts. In numbers there's not much difference between different brands, a GTX1070 performs about the same no matter who built it. Overclocking adds some, but at that level you won't notice the difference in your normal gaming.
The big issue is that the manufacturers have different quality standards. The cheapest ones may have a thinner circuit board and low quality capacitors. There's also big differences in cooling, the reference ones usually run hotter and make more noise. The most expensive variations may not be the best but the price might give some hints about quality. Efficiency in production can keep the prices down even for the best products so it pays to read comparison reviews about a certain model.
