I have friends that own a Leesa, Casper and Purple mattress. FWIW I couldn’t tell much of a difference for the few minutes I laid on them. They are all pretty good and pretty affordable compared to traditional mattresses.
I did end up purchasing a Leesa mainly because they also had a deal that made it more affordable than the Casper mattress. My wife and I have been happy with it for the last year or so.