It depends where you are in the world re pricing of the units.
In the USA right now the 8300 Core i5 SFFs are the best deal in terms of refurbished prices. I do think that those people who want an i7 Intel CPU are better off going with Haswell systems. I prefer the Dell 9020 MT. When you buy the Core i7 CPU models the price is only slightly higher or the same as the Ivy Bridge based 8300 Mini-Towers with an i7. The Haswell i7s have AVX2 instruction set support whereas the older 3rd gen systems don't. The other advantage of the Dell 9020 is that it's easier to swap out the PSU and add a 570/580 graphics card. No modding is required to do this. I also like that the 9020 MTs are closer to mATX size than Mini-Tower size. To me the 8300 MTs seem to have a lot of wasted internal space.
So yes, I think it's always important to survey local prices to get the best deal for the hardware.
Here's a current example on Ebay.com The newer Haswell based 9020 is the same price as an 8300 MT. So in this situation, the 9020 is the better choice. If the i7-4790 is available that has even faster turbo boost clock speeds.
Even if you build a new quad core i3-9100 CPU system with similar specs it doesn't compete in terms of price. You'll be paying well over $500 USD, even without a dedicated gfx card. The newer CFL system will give more years of a useful life though. A 3 year warranty on the new motherboard and CPU is also a plus. It seems that new case and PSU prices have gone up a lot lately and won't be coming down any time soon. Here's a new Asus B360M and i3-9100 CPU system I priced out on Newegg. The cost is $508 shipped before the sales tax is added. So total cost is close to about $530. A good investment but double the cost of the Dell i7-4770 MT. If one has the extra $270 to spend right now it's probably a good idea to build new. The PSU and case are significantly better in the new custom build. You get faster DDR4 ram and an NVME SSD boot drive. Some things to consider.
Prices are show in US dollars.
Total of about
$508 USD before tax.