The CPU upgrade depends on what you need to do for your system. If it's a workstation, editing or running virtual machines, I would lean more towards Ryzen for a higher core count. Ryzen works well on gaming, don't get me wrong, but I feel Ryzen shines when it's actually using all the cores it has, which, will be from the above examples -- someone feel free to correct me if I'm wrong, but a good portion of games only really utilise four cores or so.
If you were to upgrade to an i5, you could get something like an i5-4690/(k) -- which is still very relevant in 2018 if you're on a slight budget and can can't afford to upgrade to Coffee Lake/Ryzen with a brand new CPU, motherboard and RAM. If you have a budget that you are comfortable to spend on, you could upgrade your whole CPU, motherboard and of course RAM with either a Ryzen build or a Coffee Lake build.
At the end, if you go Ryzen or Coffee Lake, you will need a new motherboard, CPU and RAM. If you want to jump into an i5, the 4690 / 4690k would be a reasonable jump; however, prices on them seem to be a little higher than I remember when I got mine back in 2015, I spent around $260-ish on it and it seems now they're in the $300 area.
If you decide to do a full overhaul on your CPU, motherboard and RAM, knowing your PSU and exact case will help tremendously. I know your current motherboard is a Micro-ATX, but it needs to be known if you have a bigger case with Micro-ATX standoffs or a smaller case meant to fit the motherboard. That's just to make sure that any motherboard suggestions will fit your case.