I know there are many mods that change the traffic variety and stuff, but wich one gives the most traffic? And is there a mod so I dont see cars appearing from like 30Feet away magically?

I'm pretty sure the whole cars spawning near the player deal is something hard coded into the game. You could try upping the draw distance in game to see if that helps. As far as the traffic goes, I think most mods are just a simple change in the "settings" file in C:/Users/your name/Documents/Rockstar Games/GTA V. If you change <CityDensity value="1.000000" />  and  <PedVarietyMultiplier value="1.000000" />   both to something higher, like 1.400000 etc you'll get more traffic and variety in peds. Don't go much higher than that though, the game will crash.

https://www.gta5-mods.com/misc/traffic-variety