ElectrO_90 :
I always suggest Ryzen AMD because at least the motherboard will be working for the next 2.5 years.
If you go Intel, your motherboard will be out of date by next year.
Ram is expensive now, so that's the biggest problem as you need at least 8GB which is why I suggest second hand to keep costs down and will keep you going for the next 2 years
Oh damn I was gonna say you're right or this is the solution but you lost me at your "out of date by next year".
As someone that had 3 GPUs and 1 motherboard (MEDIUM RANGE not high quality) + 1 i7 4770k overclocked for over 6 years. You're full of s*it sir.
Besides that, he's right, getting a cheaper DDR3 system (like mine) will still run most games atm, we don't know what the future holds. But since you got a decent GPU and RAM (and hopefully PSU), you could get a used motherboard and a 4th generation Intel from someone reliable or that looks clean and cared for. That's the cheapest option. The other option is new generation system with some of the newest parts and DDR4 (just to make sure you don't have to upgrade in the future again, like I did, with the motherboard + CPU and I only upgraded other stuff, I ran with 780, 980ti and now a 1080ti, no problem)
And if you want to know which is the best from the 4th generation, you'd be lucky to get a good 4790k, the 4770k is decent but much hotter.
To answer your original question, unless you have issues with some new games, you don't need to upgrade. Your GPU even if bottlenecked will always give you the most juice/performance boost in an upgrade. And you have a decent GPU.