Not sure that I'd call myself a developer, but I do do a lot of html and css, and having a comfortable editor is hugely important to me. For close to ten years my favorite editors have been NotePad++ and Expression Web 4 (using EW4 to proof the html while offline). NP++ is great in XP because XP can be themed how the user wants, but in Windows 8.1 I have to switch to a customized dark classic theme to eliminate the white scrollbars and stuff. The customized dark theme is good for several different programs (i.e. Corel and Paint Shop Pro), but it makes a mess of other programs like Word, and so I'm never satisfied. 😉
But in Solus, I can use Geany, BlueFish, Gedit, and NotePadqq comfortably, which I was never able to achieve in any other distro (Budgie is the key for me).
If circumstances permit, I have been seriously considering coding a 'Find Column' addon for Libre Writer that would enable a list of searched words (similar to what is in Gnumeric and Calc, and is a key feature of Word 2010 (and is a necessity for my work)). I haven't made an addon for a program in a lot of years, so progress will be slow if I ever do begin the project.
And, so, yeah, for me anyway, Solus is my own personal top choice for developing website code, addons, and anything else that might resemble code.