An i5-4670k would require an upgraded motherboard. There are Intel fans and AMD fans, I am an AMD fan to the core and can and will defend them in all areas, with logic and reason, but even I, being and AMD fan will admit, that in terms of performance, Intel is currently the king. If you are after strait up performance, go find ani5-3570k, delid the thing, phase change liquid metal alloy, and OC that puppy to 4.6 - 5.0GHz.
If you are heart-set on AMD, to support the underdog and an interesting and unique architecture, although it is much less efficient, then go with an FX-8370(E). I like the "e", cuz when you aren't gaming, it'll use a lot less power than the standard 8350/70, however, you can still OC that bad boy to 4.6-5.0GHz as well, and it's not a bad CPU at all, regardless of what Intel fans say. It'll kick ass at multi-threaded situations that can use over 4 cores. It, contrary to what Intel fans like to believe and what AMD marketing idiots like to embellish as a selling point, it only has 4 cores. Each AMD "module" has two half cores sharing the same resources. A single Intel core is equivalent to a single AMD module, which is why the FX-8350/70 is constantly head to head with the i5 quad cores rather than an i7 or above (hex cores, etc.), and with the FX, costing about 50% less than its i5 counterpart, it ends up being better on the price/performance ratio. Yeah, it'll use more power, but since you're talking about a desktop and battery life isn't a concern, power consumption doesn't really matter.
You're okay with either option you go with, Intel or AMD. If you can save money going with AMD and that is what you're trying to do, go for it imo. Especially with Mantle, and DX12 in the near future, bringing so much performance out of AMD CPU's, they are actually becoming viable options.
Good luck!