I think personally, you have the i5 now, which is going to limit you a bit going forward due to lack of threads. I think I would do these upgrades.
Power supply
Better CPU (something like an i7 4770k or similar)
New GPU
If you go for the other upgrades, I think on GPU, you should look at either the RX 580 or the gtx 1650 super.
The 590 is not a bad card, I had one for a short time, but if you're staying at 1080p 60hz, the 580 is only just behind it.
Have a look here.
While technically a new GPU, the Radeon RX 590 is in essence the same RX 580 with a 15% overclock. What we have here is Polaris 20...
www.google.com
Basically the 590 is an overclocked 580. The other thing you need to consider, going forward, the i5 will limit you. Quad core cpus with only 4 threads are starting to struggle in some titles. Battlefield 1 for example was one example. I'm sure there are a lot more going forward. So I say upgrade that, sell your i5. Didn't see in the opening post, but if you don't have an SSD, use the funds from your i5 to get an SSD which would help it just to feel faster in day to day use. If you have one already, put the money aside towards a new system fund, or save for a new display.
I know the RX 580 isn't as flashy as the 590, but compared to your 750ti, it will be a HUGE upgrade. I had a Vega 56, but downgraded to an rx 580 since I got a good deal on selling it. And needed to do the responsible thing and pay some bills. But in the process I got a used rx 580 for about 100 dollars.
I did also purchase the new Jedi game with Christmas money. I started playing last night a little, keep in mind as someone who was used to the Vega 56. I play at 1080p though and have a 144hz monitor with freesync. However, I set the graphics to high settings, and it was perfectly fine. No I'm not getting 144 fps. But at good settings, it was playable and I could enjoy the game on it. I've used a 1050ti in the past, which was faster than your current 750ti. Let me tell you, even an rx 570 or 580 from what you have now is going to be a massive upgrade from what you've got now.
If you feel like it, look around in the used market the 580s on what can still be had around 100 dollars if used doesn't scare you, since there are a lot of mining cards being sold these days. But an i7 would max out your current platform, and the newer card would still let you enjoy some nicer visuals. The PSU upgrade is wise for the future, then it and GPU can be carried to a new build later if you wanted.