well nobody asks you to buy skins :) ? Fortnite is more fun for me but its for sure a matter of players own preference.
cs go is same old, nothing new, nothing changes - gets boring
fortnite on the other hand has so many options - (new weapons, options, building system, variety of weapons, nades, etc etc)
fortnite feels like a game that gives the chance to win for players who have just started since you can outplay your opponent by setting up traps, using camouflage outfit, rockets, buildings. In cs all what did matter was to have a working average brain and decent aim (was global for 4-5 months straight and quitted afterwards)
in the end it all comes down to a individual itself what it likes more.
Before I played CS I thought that fortnite is big piece of shit but now I actually like it a lot.