So I revive my old thread as I have take my decision and purchased the parts for my PC.
I paid 2.600€ for a Skylake i5 (3,5ghz), 16G Ram, A 980Ti GPU, 500 GB SSD, a 4k 28 inches screen, mechanical keyboard and nice gaming mouse.
The closest Imac would be the 5K with a much less powerfull GPU. That would cost me 3.529€
I have almost migrated all my data to my PC now and I am happy with it.
I know some of you will say that I will have plenty of issue with Windows. That's not my experience. I can't say that my experience with my Macbook Pro is true to the "it just works".
Some will say that I cannot resell my PC as well as an Imac. Not an issue, I almost never resell anything.
And some other will say, that I will enjoy my purchase. And that I do