Should I go for i7-6700K or i7-4790k ?

You won't notice a difference between the two CPUs so compare other features instead. (Drive speed, USB 3.1, RAM, etc.)

The i7-6700k is the latest chipset/socket of course and will be upgrade-able in the future as the 4790k will not (spare the 5775C).
 
i7 6700k vs i7 4790k
Performance: not noticeably different unless you are using benchmarking tools.
Features: i7 6700k platform supports DDR4, which could be more future-proof. i7 4790k supports only the good old DDR3.

If you really need really powerful platform and ready to pay luxury price, i7 5930k is also an option.
If you do the video/rendering editing professionally and heavily, I would look more to i7 5930k.
 


Some people say 4790k is very good that's why I asked this question.. But still if budget is not an issue that doesn't mean one would like to spent without reason. In case "A" has very little reason to spent money on I will obviously go with "B". Like "guanyu210379" said i7-5930k is better for my work so I will look into it.
 
But surely, if one cannot justify the extra money, then budget is an issue? To me, "budget is not an issue" means that you may as well go for the latest and greatest.

Anyway, the 5930K is a great CPU for the work you need to do, but expect to pay a big premium over the 4790K and 6700K ($200-$230 USD). Premiere Pro will utilise all of the available CPU threads, so you'll certainly see increased productivity with a 5930K.
 


Look, I don't know about others but if budget is not an issue then it doesn't mean I will spent on a product which has very little edge over another. 5930K is good for my work so I order it now over 6700K because fortunately don't have budget problem. But if someone tell me to choose between 6700K and 4790K then I will ask people which one is best, then will buy any of them. It's my personal thinking :)
 
The 5930k is a waste. Either get 5820 or 5960. The 5930 has the same 6 cores as the 5820, yet it is 50% more expensive. And before people start the PCIe lane argument - the 28 lanes that the 5820 comes with are perfectly enough for a workstation.