I'd suggest you drop Quanta Plus. It hasn't been released since KDE 3.x days.

Maybe you could also add eric/eric3 to the mix. It's a good IDE for Python.

I've been missing GoLand (Gogland before November). It's by far my favorite IDE for Go (golang).

What about Sublime Text? Its one of the best

SeaMonkey is a really cool web-page authoring interface - It's the ONLY WYSIWYG editor I could find that actually worked for me on Linux Mint (and I have tried pretty much most of them on the above list).

I decided on BlueFish as it has great auto-complete features, informs you where your tags begin and end, plus suggestions on tags as well as information on what is available on each tag. Not to mention tons of help. All it needs is a WYSIWYG interface and it will complete an already fantastic editor.

So BlueFish might not be a WYSIWYG editor, but it turned out to be the best tool for the job I needed to do.

It should be pointed out that GNU/Linux itself is a proper IDE if you know how to use it. No weird monolithic packages needed.

Another category which is changing for me in 2018. I have started to play with Acme and it's awesome.