For upgrade, there are several:
low-end (today's standards) but still good upgrade - GTX 1050 TI, 1650, 1650S (latter is equivalent to GTX 1060 6GB)
medium-end, solid for 1080p gameplay - GTX 1660, 1660S, 1660 TI
and high-end is any RTX series GPU. Even the weakest, RTX 2060, is enough for 1440p (2K) gaming.
Personally, highest i'd go, would be GTX 1660 TI. It bottlenecks your current i5, but once you upgrade and go with new CPU-MoBo-RAM combo, 1660 TI is solid for 1080p gameplay.
Now, if you don't want to bottleneck your i5 that bad and/or don't have money for 1660 TI, 1650 and 1650S are also solid choices. 1050 TI is also good but gaming wise it can do 720p. 1080p, maybe.
Edit:
To give you complete list of Nvidia GPUs, better than your current one, ranked by average performance and listed from worst to best, GPUs would go like this;
(each following GPU is ever so slightly better than previous one)
GTX 570, 660, 580, 950, 1050, 660 TI, 760, 670, 1050 TI, 960, 680, 770, 1650, 780, 970, 1060 3GB, 780 TI, 1060 6GB, 1650S, 980, 1660, 1660S, 1660 TI, 980 TI, 1070, RTX 2060 and so on, towards the high end (i don't see the need to list high-end GPUs).
So, if you don't mind buying 2nd hand and few gen older GPU, you could get nice upgrade even with GTX 780, 970 or 980.