There's different generations of i5, no such thing as 'regular' i5. Skylake is intel's naming scheme for 6th generation cpu's, haswell/devil's canyon were the 4th gen, broadwell was 5th gen etc. The difference is more or less in the platform/motherboard options. More m.2 and sata express ports, more usb ports, usb 3.0/3.1, dmi 3.0 instead of 2.0, ddr4 instead of ddr3 etc.
You could probably get an i5 6500 for around the same price as a 4590. Gaming performance will likely be similar, just on a newer platform. There really isn't any better performance at that price, as performance goes up so does price. Either the 4590 or 6500 should play games well and most multitasking.
If you want to do other things like streaming, a lot of video editing, you might consider a 1231v3 xeon with an h97 motherboard. The xeon is a little more expensive, around $243 and has no integrated graphics but it has hyper threading like an i7 does.