Personally speaking I would avoid AMD CPUs altogether and go get the i7 4770K.

Doesn't matter, even an AMD fanboy at this point will admit that intel CPUs are much better. I think Pemalite who's a fan of amd graphics are using intel CPUs too and so am I. 

Intel CPUs are clearly better but I don't care. The AMD FX-8350 seems to be a very strong CPU.

Ram speed is totally irrelevant unless you have integrated graphics like AMD's APU's.

Just get 8-16Gb of DDR3 1600mhz as that's the sweet spot. (I would lean towards 16Gb as that's going to be plenty for years to come and Windows can cache that bit extra.)

As for GPU's, you can't go wrong with the Radeon R9 290.
However, I wouldn't bother buying a Radeon R9 290 if all you are going to be gaming at is 1920x1080, you would be better served with the Radeon 280/280X/7950/7970. - Whichever you can find cheaper.
You would want at-least a 2560x1440 monitor to stretch the R9 290's legs.

For the CPU, I would opt for a Core i5 4670K or 4770K, there are games out that just don't push the threads needed to make AMD's CPU's kick into another gear, plus you would save money on the energy bill.
I would only go AMD at this point unless you are on an extreme budget or intend to use software other than games that can use all 8 threads or intend to overclock the CPU with some exotic cooling like Helium.

AMD won't be updating the AM3+ socket in 2014, there might be an update in 2015 or they may cancel the entire platform to focus on FM2+. - So you might be left in the lurch with no option of something faster.

On my FX 8120 system, demanding single and dual threaded games *really* struggle, like StarCraft 2 when there is a ton of units on screen. (Think: 600+ with Physics)
Or Sins of a Solar Empire once players start to lay down lots of land mines.
And don't even get me started on Arma...

I always like an underdog, AMD is a good company, but when it comes to your wallet you need to make the choice, just remember by choosing an AMD CPU you won't be getting the best all-around performance. - The performance may be "good enough" but that's up to you.

So getting 16GB RAM 1600mhz is a good choice? It's the cheapest 16GB I can get?

So you have a FX 8120 system but also the Intel system in your sig?

I also like those demaning stratety games with tons of units on screen. But I am willing to bet and take my chances that an FX 8350 will do the job well enough.

How much difference is there between an FX 8120 and an FX 8350?

Yeah 16Gb is a good choice.

I have several systems, Core i7 3930K, AMD FX 8120, Phenom 2 x6 and currently an old Core 2 PC. :P

As for your last question, the difference should be about this, just a little larger:
http://anandtech.com/bench/product/434?vs=697

I do have my fx clocked at 4.8ghz though and have the fx patch for Windows.

I still recommend the 4770K or 4670K though as the differences are pretty big (Almost double the single threaded performance with Haswell, socket will also get a CPU upgrade next year.), I tend not to be loyal to a specific brand if the alternative is a better choice in terms of performance.
http://anandtech.com/bench/product/836?vs=697

I'm sure an FX-8350 will perform fine on integer workloads but it falls way behind when attempting to go against applications that need the floating point performance and even more behind when depending on single threaded peformance.

That goes without saying because of how AMD designed the chips where they shared the floating point unit across 2 "cores".
But that was for a reason, which won't come to fruition for a few years yet. (Having the IGP take over some of that task.)

That was a bad idea in general. What AMD still doesn't understand is that there is a need for serialized floating point and integer workloads. AMD fusion was a decent idea if not for all the delays but AMD bulldozer was a total disaster, period. It mostly only shows incompetence on their CPU division. I think AMD is better off copying intel's core architecture.

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