The GPU market right now is pretty crazy. Last gen are ending production, and the next gen are almost impossible to get ahold of. That being said, you should probably wait to get a new GPU if your old one is still working properly for you at the moment. As for that budget, there are not many options. More budget cards may be released soon, but the cheapest new GPU for the next generation is currently $400 US, though cheaper ones may be revealed later. If you really need one now, the GTX 1660 Super or GTX 1660ti would be the best fit, but you might be lucky enough to find a RTX 2060 for that price. I still recommend waiting for some time.
What graphics cards from the Radeon / amd line should I look at which are comparable to them cards ?
I was looking for one soon because Ive got half a pc from updating the CPU motherboard etc on the first pc .
The issue is budget vs value vs gains. To get worthwhile value and gains would mean a higher budget, there's some gains to the 1600 series cards over the 1050ti, but not enough to justify spending £200 on. If you had to, I'd be shopping ebay.uk etc for a used 1080-2060Super, as much as I dislike used gpus, that might be the better option.