It's not a competition - OLED leaves its "competitors" in the dust. It's like arguing over a Steam Engine vs Gas.
I've been researching both technologies a little bit, but not a lot yet.
I'll be in the market for a quality 75" 4K QLED or OLED and have been looking at Samsungs, LG's and other various models.
I did watch a lengthy review of a QLED vs an OLED on youtube with the TV's side by side, not sure what size they were, 60-70", and the QLED's image quality was nearly as good in this specific comparison, as shown clearly by the tester with both running 4K content. OLED was better in just about every facet, including image quality, but the tech can suffer from burn in. They were both $2000+ panels.
The worrying part was the QLED not having good viewing angles...amazing this is still an issue with LED panels.