I wish I could say, “just buy X or Y” but I have close to zero experience with trying out different brands. The most i’ve done is compile lists from various sources.
So my not-so-great answer would be:
If you want one with a FOSS driver (most likely to work out of the box with all distros) there’s a list here though to my knowledge the best is Wireless-N.
For wireless AC/AX/AD with proprietary drivers there’s a list here.
Both lists are a work in progress and non-exhaustive. If you have a good time with a particular card i’d love to hear about it and may add it to a list.
As Kubuntu closely follows Ubuntu it’ll have the support for a lot of wifi with proprietary drivers out of the box but may need a package installed from the repo depending on what you get.