To be quite honest I'd have to say that Fortnite is better than PuBG for a few reasons. The first is that Fortnite is more than simply a Battle Royale game, which is something that people seem to forget. That is that it started out as, and has a fully fleshed out PvE mode which is honestly just as much fun, if not more fun then the BR mode. Next, the game is not out to take itself super seriously, much like PuBG is, which in my opinion results in a community which is less toxic, despite the fact that Fortnite has the largest community. Building off the previous reason... the game is much more of a treat in terms of style to look at. Items are exagerated in their proprtions and just fun to look at... including the weapons as well. Finally, you also have the building and crafting system that is built into the BR format that adds an additional layer to it. Finally, I enjoy the lack of artifically, "limited" clothing that exists in Fortnite vs that of PuBG ( 300+ dollar virtual trenchcoat anyone? )
That said, the only thing that I really do enjoy in PuBG over Fortnite is the fact that you can create a consistent character and work on customizing him/her. Where the character customization in Fortnite is very very limited by comparison.