Every single time I come at different wikis I get an annoying dialogue with the question which editor to be used, etc etc. Sure, it is okay to ask this one or two times, but asking this 40 times in just one day if someone works a lot across wikis is insane. (Sorry to say that.)
Also I see no option to set this in my preferences...
This results that if I delete all the cookies in my browser (to get rid of tracking cookies from commercial websites, not related to Wikimedia) I get all those dialogues again!
And sometimes it loads so slow that I already have the edit screen where I edit and then the dialogue appears and blocks every edit, unless I hit the enter key (etc) during typing that make it disappear, while a part of the typed text is missing.
Third, even after clicking "edit source" in some wikis, the visual editor (!!) loads, and after the typical slowness in loading of the visual editor, I get still that same dialogue of which editor I want to use... No, if I click "edit source", I really mean I want to edit the source code and then I do not have a secret wish to use the visual editor anyway.
Summary: I think this dialogue is great for new users, for experienced users it is highly annoying. Second it is annoying that such can't be set in ones preferences.
I have no idea what would be the best solution, but the current situation is far from user friendly.