I haven't really thought much about accessibility TBH, especially around KDE. At least not outside some basic stuff, like color schemes and the like.

I haven't used KDE much but from my little use i found it better than GNOME - mainly thanks to Qt - but still leans a bit too much into the flat trend (especially some newer things that use QML instead of Qt Widgets). Still, if i absolutely had to choose between the KDE and GNOME i'd choose KDE. Fortunately there are more choices and if i had to go with a desktop environment that currently exists (as opposed to my fantasy one :-P) i'd go with XFCE.

Though in practice i use Window Maker, but that is mainly out of habit as it doesn't exactly match what i'm talking about. But I do use Thunar as a file manager and Mousepad as my notepad-like text editor.