. I try to find the best system that will help me achieve my desired photo.
Wow, that is an expensive option - but if that is the case, go for a Hasselblad/Fujifilm/PhaseOne medium format type system.
I am not just looking into the bodies but the lenses too. Are the lenses of good quality?
Yes. Modern lenses are very good, plus you can use any old classics on mirrorless. I personally hold to the idea that there are no bad lenses, just lenses that are a bit more difficult to use, or which have a certain 'character'... but if you are looking for sharp contrasty and fast focusing, any system will deliver.
Is the af of nikon as bad as youtubers say (i know that is exaggerated but i have to ask)?
Of course not - even if it isn't as good as the best of the competition, it is still going to be effective in most situations - after all people did manage to take good photographs with film-era AF, or even with manual focus.
is there any aspect of your camera or the system in general that would hinder you from creating?
My talent is the limiting factor. I would expect that to be the case with most photographers.
I have a tendency to have the latest gear. Thats because i start fresh and i want the latest technology to work in my favour.
If you are affluent then you can afford that. You get more for your money if you are prepared to have last year's model, but if money is no object...
I have the opportunity to buy a d810 with a whole bunch of lenses but if i am to drop so much cash i will buy the latest
The D810 would be a great option if the price is right. I don't think anyone wwould feel very limited by such a camera.