What is best gpu for older PC

So its been bugging me for sometime, I have a bunch of parts sitting there stuff from 2008 / 2009, motherboard with pci-e x2 support, some ddr2 ram, a few athlon dual core cpus, etc.

While cleaning out some old crap I found a bunch of cd's from way back when... stuff like Quake, Unreal, Need for Speed, Carmageddon, Rollcage, Mortal combat 'you get the idea' a lot of these games were older pre-2000 games I remember playing and enjoying a lot when I was younger most of which were either dos based or win xp compatible... So I thought maybe I should recycle those old parts into some sort of rig that can cater to this.. but the system needs a gpu.

I could pickup something older, a gpu from either a 6xxx to 9xxx series graphics card ie: 6600 nvidia card or 9600 gt or maybe even an ati 4850... but looking at some of the prices of second hand cards from that generation sellers in my country are trying to sell them for 30 to 40 dollars or more some as high as 60 or 70 bucks...

Now when I think about that it didn't make any sense to buy a used old card... but I still need a card for this old machine that works with win xp, with directx 9 support, for older games.

I want to ask of the newer budget cards, so this includes but is not limited too the Nvidia 610, or 700 series cards, or the AMD R5 series cards which one is best bang for buck but also best for compatibility for an older rig and which of these have adequate driver support for older operating systems?

I recently sold my 2012 GTX 660 for $60.
At one time it was the world's most popular GPU (Steam survey), so they should be easy to find.

I remember the 8800 GTX was one of the best if not the best. Also the 4870x2 was a true beast.

A Radeon HD6850 worked well for me with a Q6600 CPU at stock speeds - noticably better than the 8800 it replaced.

I used this with Vista....

I had the HD6850 too but lasted like 10 minutes and than died without a reason lol Immediatly replaced with a 6870 (now dead too after 4 years of service).

I recently re-built a 7 year old Q6600 OC to 3GHz and tried both a HD7870 2GB and a GTX 670 2GB on it and it was still able to play some recent titles at playable frame rates with reduced options. The 670 was 10 fps on average better than the 7870 so maybe look for cards around that class.

System base unit sold via this forum too and no complaints from the recipient. I kept the GTX 670 though!

Oh and now it's running in my spare i5 3570K system and runs Far Cry 4 at 1080p with high settings.