Aerocool makes nice cases, I've never used konlink, but from the sounds of things around here they be like those CiT items which I have had in the form of a micro tower with a 500w included psu, for the old basic build I had for general use and kodi it was fine, but the material seemed cheap and flimsy which is not what I'd have liked for £40 brand new in a shop, but then I didn't buy it to keep.
As above, go with what you think looks the best and make sure it takes what you need, while cubes are handy, if a disc drive is required then you will be limited in some aspect or have to pay a certain premium.
Haswell builds are good if it involves saving money for other parts, but obviously if you can afford skylake/kabylake then you might as well as it makes more sense, I have haswell, but I got mine back in 2015 and if the game(s) you play require more cpu grunt then pretty much any i5 will be better than an i3 or pentium as that dual cores, but has hyperthreading to aid like a quad, but still not a quad at the end if the day, I'm not a heavy pc gamer anymore nor did I have the money, so my i3 suited me just fine.
