Is it worth it to “upgrade” from GTX 970 to RX 580? Have a 144hz Freesync monitor.

Not sure if it is really worth it. Used ones are found online for ~$100-$120. New are almost ~$180 for the 8gb from what I remember.

My monitor could definitely take advantage of the 580.

I could get probably $70 after shipping for my GTX 970.

Opinions? I don’t know if the FPS increase will be worth the money. Should I invest a little further for a 5600?