I really can't stand 3rd person because it gives too much of an advantage to the defender. You can just camp and peek a corner, and you can see everyone coming, but they have no way of seeing you.
In 1st person, the only way you can see someone is if you peek and expose your face.
Other than the lack of 1st-person only, by biggest problem with Fortnite is traps. One of the biggest differences between Fortnite and PUBG is how much faster-paced Fortnite tries to be.
Smaller map, smaller/fewer/closer together compounds, and yet the same amount of players. Faster bus, WAY faster gliders, and I believe faster circles too. Plus the building mechanic can enable you to build over obstacles rather than traveling around.
But then you add in traps to the game, and you're forced to slow down inside structures and check every room you go into to avoid insta-death. I think the slowdown that traps add just clashes to much with the otherwise fast-paced game that Fortnite tries to create. I've had games where I'm the last man standing in a 4-man squad and I'm holed up inside a house. I successfully fight off a full squad of people, just to insta-die to the trap one of them placed in the house. It really is a moodkill to me.
My favourite movement mechanic in PUBG is the autorun because that's what you're doing for 50% of the game.
I've spent considerable amount of time in Fortnite running as well. At least PUBG has vehicles.
But I'd sooner play it over PU's Chinagrounds.
From what I've seen and heard, most of the Chinese players stayed in 3rd person.