Question Which gpu should I buy?

[perdboy]

So one of my friends is upgrading his pc and wants a gtx 1070. I offered my msi gtx 1070 for $250 and am planning on buying a new pc for around $350 or $400. My first option was the rtx 2070 and I was also thinking about getting a gtx 1080. I am willing to obviously buy it used and get it at around $400 or less. Anyone have any suggestions on which card I should buy.
My rig
ryzen 5 2600
Asus b450 f gaming
EVGA 750W psu
Corsair Vengeance 3000mhz ram

 

[EndEffeKt_24]

The new card we would be looking at here would be some sort of 2060 or vega 64. 400 or less will not get you a new 2070.

That leaves us considering the 2070 used (but might be difficult to find) or a 1080. But you would get a used card with most likely no warranty and in unknown condition.

If you find a 1080ti for that price used I would take the gamble. But in most scenarios I would just keep the 1070 and be happy. Mine does 1440 gaming just fine. No need for an upgrade right now.
I would definetely NOT sell my card off before verifying that my purchase works as intended.

Cheers mate