GMC AT4 is a beautiful truck, cant go wrong there in terms of looks. My brother had terrible luck with GMC products so i avoid them but i know the same could be said for Ford based on youtube reviews. You get a 3 yr bumper to bumper warrant with the Tremor to iron out any issues but like you said, you might end up in a situation where the truck is in the shop for weeks/months and you are making a payment for nothing.
One guy i follow on youtube sold his 2021 F150 Tremor even though he loved it and swears no one should buy a Ford product built during the 2021-2022 period. He might be right but i do need a truck now so i don't really have a choice (unless i stumble across something used i really like).
edit: i am hoping when my F150 Tremor arrives i will love it. But i am also prepared for the bottom to be coated with rust, stereo to rattle, and all the other issues we see on the forum here.