Upgrading to a new gpu. Need help?

Alright Lads, listen up.
Around 1/2 years ago I came here when I built my computer. (Best thing I did, it helped me a lot)
Anyways, now we've reached that 1 1/2 year milestone. My PC has become a bit outdated, so I am looking to upgrade my GPU and I was browsing around the internet looking at local deals and have come across a couple cards which I would like your input on.

Gigabyte R9 280x
Asus HD7970
GTX 770
(These are all secondhand)

Current Setup:
AMD Athlon x4 760x
8gb HyperX ram
1 Tb WD Blue
R7 260x
Some 500w psu + case bundle

If you're looking at those cards I'm assuming your price point is $80 - $120? If so, you're right on the money with those choices. The older AMD cards will be packing more punch than their nVidia counterparts, but both are good deals around the $100 mark. Also, the 7970 and R9 280X are for all intents and purposes the exact same card. If you find 7970s for $20 less, it's the better option.

One final note on those older AMD cards though, they could have been used and abused with crypto-currency mining. Those cards are often still going to work but will have a higher likely hood of kicking the bucket before long.

I owned a 770. 4GB vram (even at 1080, yes) and find the best cooler you can. The more clocks you can squeeze out, the better. Get a good one and you'll be happy with it.
Can't say anything about the AMD cards, just out of ignorance, never had first hand experience with one