Which processor should i choose?

Well if you have the money, go for the 3930k. It is true that you only need and i5 for gaming though. But if you can afford it and like the best of the best, go for it. Just be aware that the new enthusiast cpu's from Intel, Ivy Bridge-E, are expected to arrive soon.

which i5 would be best? i5 3570K or

And what would be the best motherboard recommend for the 3930k?

One of these two: Both of these are great for gaming without question

Intel Core i5-2500K Sandy Bridge 3.3GHz $219
http://www.newegg.com/Product/Product.aspx?Item=N82E168...

Intel Core i5-3570K Ivy Bridge 3.4GHz $214
http://www.newegg.com/Product/Product.aspx?Item=N82E168...

I would get the the 3570k because it is very close in price and is newer. Only go for the 2500k if you are going to overclock past 5ghz.

I would go for this X79 motherboard for the 3930k:

Asus Rampage IV Extreme:
http://www.newegg.com/Product/Product.aspx?Item=N82E168...

I like the i5 cpu - choose the one you like the best but I would not choose that MOBO as mentioned above. That is way too much overkill for a gaming build

It is overkill but he did use the words "best" and "money is not an issue"

Is a ROG Maximus IV Extreme-Z any good for 3570k?

Not to just repeat what the others have said but, the 3930k is not really going to help you. It's awesome when it comes to video editing and such, but it the plan is to make a gaming-computer you will get more or less the same performance from an i5 3570k.
The 3570k CPU is -great- for gaming, and the money you save you can throw into another GPU for SLI/Crossfire, an SSD, etc etc.
It's also very easy to OC (ofc this varies from chip to chip) and if you throw on a 212evo or something similar i can promise that you will be happy with it.

Best of luck on w/e you end up with : )

There is this E3 1230V2 that might be an option if you can find a retailer that stocks it.
It is only 100 mhz slower than the i7 3770 but cheaper by about $50. It can overclock using the turbo multiplier to 4.1ghz. It also carries the same regular price of a i5 3570K and with HT, it can out perform a i5 3570k at 4.1ghz (don't think the 3570k can go much further than 4.3~4.5)

http://us.ncix.com/products/?sku=70541&vpn=BX80637I5357...
i5 3570k

http://us.ncix.com/products/?sku=74987&vpn=BX80637E3123...
E3 1230V2

http://us.ncix.com/products/?sku=70539&vpn=BX80637I7377...
i7 3770

http://us.ncix.com/products/?sku=70540&vpn=BX80637I7377...
i7 3770k

Thank you all for the answers helped clear a lot, I think I'm going to go with the 3570k, one more question what would be the most ideal motherboard for it? And I think might add two GPU.

http://us.ncix.com/products/?sku=71114&vpn=P8Z77-V%20LK...
This ASUS board offers a good amount of connectivity and is reliable and relatively cheap.

For GPU, you could crossfire 2 7850 or 7870. Getting a single high end card is a better option though since there would be no issues with SLI or Crossfire scaling. For single card, I would look at the 7950 Boost or the 670. The 7950 Boost offers a lot of the performance of the 670 but is quite a bit cheaper
http://www.techspot.com/review/603-best-graphics-cards/...
You can look through the review to check for performance in the specific games you play. The review used the latest drivers and prices form both sides. The end chart is slightly misleading so you should read through the reasons they give for their choices. The 7870 should have take the 200-250 bracket at $240 since it performs better than the 660. The 660ti should also have lost to the 7950 Boost since the 7950 fits right into the 250-300 price range @ $300.

I think ill go with that motherboard, and with the GPU i think ill just buy a 7970

so this is kinda what I'm planning to get

Asus P8Z77-V-LE-PLUS $159
Intel i5-3570K $227
Samsung 830 Series SATA3 256G $195
WD Black SATA3 1TB FAEX $99
SATA Blu-Ray Combo LG $55
3G 7970 Asus $459
16G Kit 2400(8Gx2) G.Skill Trident-X $145
OEM 64 bit MS Win7 Premium $136
SuperFlower SF-1000R 1000W $159
Corsair Graphite CC600T White $185
Corsair H80 $129

all up $1948, what do you think?

It's a real solid build. I think you're going to be real happy with it.
The H80 CPU cooler is alot more pricy than the 212evo but, that's your call

would the 212evo be enough?

It depends on how much overclocking you intend to do. I have mine at 4,2ghz with a 412s (more or less the same as a 212evo) and i've never seen it go past 69degrees. Idle temps are ~27-30degrees.
The i5 3570k + 212evo is a popular combo for people that wants to OC 4-4,3ghz. 4,4 and higher i would recommend something more powerful, but if you're lucky and get a good chip you would be able to keep 4,4-4,5ghz and still get good temps with a 212evo.
You can also lower it a couple of degrees using the push-pull solution (where you have one fan that pushes air through the cooler and one that pulls air in the same direction).

how would a Enermax ETS-T40 be?

I don't have any experience with the ETS-T40, but as far as i know the performance is fairly similar, but it's costs a bit more than the 212evo.
If the price is more or less the same where you shop for components then you should do fine with either of them.