The "underqualified" part comes from her frequent retcons of worldbuilding elements, and sloppy plot points(many, MANY problems are solved with tactical use of polyjuice potions or the literal time machine "time-turner" which is conveniently lost right after it's revealed and used by Harry from Hermoine, but they're an uncommon item that every wizarding government branch has MULTIPLES of!). It's very clear it was all made up as the books went along, and elements that should've been closed up or abandoned were instead built upon with even more rickety bullshit.
Contemporary series off the top of my head were
- Artemis Fowl
- Eragon series
- the Mortal Instruments series
- the Percy Jackson & the Olympians series
- Guardians of Gahoole
These all got movies later(I think), presumably based off of Harry Potter's success but despite there being arguably better books out there, their theatrical releases got butchered(especially Eragon's from my memory). A few one-off books did well, I particularly liked the film adaptations of Paper Towns, Perks of Being a Wallflower & Ready Player One, even if they weren't runaway successes at the box office & were middling to critics. I think Eragon & Percy Jackson had the most potential to rival Potter as worldbuilding extravaganzas that could've been made into merchandise & theme parks, but for whatever reason weren't handled correctly.