I'm thinking of rewriting a plasmoid that I made using python. But before I start, I want to know what language and framework plasma devs prefer new plasmoids to be written in.

For language the main candidates seem like c++ and javascript. Which of these is more preferred at this time?

And for framework, is it possible to make plasmoids using QML right now? Or should I just use the normal way of making plasmoids? If I choose the normal way, would it be easy to convert it to use QML later?

In terms of the best for easy distribution, Javascript, followed by any other scripting language would be best. The Plasma developers may have a recommended language though.

With regards to QML, I would suggest contacting the Plasma developers on their mailing list, plasma-devel@kde.org.