I'm not talking about the life of the hardware itself, but moreso the longevity of how long you could play the newest games at decent quality/performance before that particular GPU was no longer viable.
Myself, I'm caught between my GTX 970 and 1070. Both cards lasted a very long time before game requirements surpassed them. In fact, I have a good feeling the 1070 is still a great option today. I've just eventually upgraded to a 1080ti and haven't looked back, so I can't say for certain.
What about you guys? What GPU did you get the most reliable gaming years out of?