Well there is a big possibility that I will get 1000$ in the next few days and since I have been without a pc for the last year I want to buy a new one.

I was thinking on this one: http://www.amazon.com/dp/B012AO2GSW/ref=psdc_565098_t1_B00SV7IU8S

Or this one (with specific parts, some chosen by myself): http://pcpartpicker.com/p/ryWZpg

Having in mind that shipping will cost 200-300$ and Amazon makes shipping WAY stressless Im thinking on getting the one from Amazon.

Opinions? Which would be better to run games like GTA V, Fallout 4, The Phantom Pain, The WItcher 3, etc? Any other rigs you think would be better with this budget?

Between these 2, I would opt for the I5 based config. AMD FX are already obsolescent, and the price of that config is too high imho.

To keep it short, the FX cores are less efficient in single core operation, and applications using multi-core tend to fare better with intel CPUs. If you really want a FX, opt for the FX6350, it received some improvements over the 6300.

Now, if I were to build a config with your budget, I would opt for a more recent CPU. I5-6400 or 6500, and couple it with a Nvidia 960 or 970, or AMD R7 370 or R9 380.

I don't mean to come off as rude but $1000 isn't going to build a 60 fps machine for the Witcher 3. Maybe ibuypower.com would be a smarter choice.

How about this one?

http://www.tigerdirect.com/applications/SearchTools/item-details.asp?EdpNo=9771938&CatId=11973

Saved you some room to buy a keyboard and monitor.

*** Make sure rebates can be redeemed in your country.

Can I suggest CyberPowerPC? When I used them in 2009 I got an absolute steal for around 600 dollars including shipping. I'd assume they're still good and you should be able to get a custom machine built for 1000 that trumps anything you can get at Amazon. Even in 2015 with a graphics card and some memory my machine is still able to keep up with most modern games.

What about OS ?

Only 4GB?
I'd get more RAM for sure.

I agree, i'd get 8 or 16 GB of RAM if i was buying new pc, not to mention SSD. Intel i5 is much better option for gaming than Amd right now and it would fit in your budget.

A quick check tells that Wither 3 demands a minimum of 6GB of RAM and I KNOW I have seen games here which demand 8GB, just cannot remember which one(s), so 8GB of RAM is the minimum in a new gaming pc today. A 64bit operating system should be a given. Two fast cores + hyper threading OR more cores also needed. An SSD, even a small (120GB+) one, makes a lot of sense especially if you only pick 8GB of RAM but is not a must. Where I live, a Geforce 950 lies in a sweet spot price-/powerwise.