At the moment if you can do without spending £££ on a pc thats probably your best bet,wait for intel and amd to bring out the next generation cpu. Theres a few things to know before buying a pc at the moment and I`ll list them below.
1. core for core they are weaker then intels fastest I5`s but a FX8350 can be overclocked to around 5Ghz which makes them more evenly match,to do this you have to have a decent cooling system i.e. water cooler custom or a aio (corsair h100) or equiverlent and a decent mobo. The I5`s can also be overclocked.
2. Amd mobos only come with pci-e 2.0 slot not like intels mobo which have the 3.0 versions,this will start to cause a problem as gpu`s are start to hit the limit of 2.0(think they are just about there now with nvidia`s 900 cards)
3. The fsb on fx8350 is set to handle 1866 and I think Intel`s run of the mill I5 and I7 are only 1600(not the extreme versions)
4. Cost where you can buy a intel i5 4670k for about £165 and amd fx 9350 can be had for £125 (prices from Amazon)
5. steer clear of I7 cpu extra cost but no real performance gain for gaming.
6. I think the AMD fx cpu`s are coming to the end of their life as they need to get more performance from each clock cycle,I don`t think overclocking to 6ghz is gonna happen soon (just my view). With newer game using more cores the I5 is stuck at a max of four cores at the moment mayble Intel will bring out a 8 core £300 version.
At the moment I`m running a 8350 @4.2Ghz with a amd r9 280 and it plays all the games I play at 1080p with no real slowdowns but I`m playing crysis 2 and company of hereos 2,I will get to newer games. I was speaking to a chap on here and he built a fx8350 and a r9 280x and was very happy with it and was playing watchdogs,I think max out.
(It kills me to say)All in all just for playing games that only require 4 cores I think it has to go to intel with the way things stand,you should get the fastest I5 you can get with a decent gpu and 8-16gig of ram, don`t scrimp on a cheap psu as you really do get what you pay for and it powers everything. Get it all as cheap as possible and save your £££ for the next gen.