<p>I think writing in HTML is <em>very</em> frustrating. It can be particularly difficult to write it on a mobile device due to lack of easy access to special symbols.</p>
I guess the answer depends on many factors; personal preferences and also the project’s context play a big role; personally I’m surprised how often I choose <em>HTML</em>.
I'm assuming this excludes laptops, so we're talking tablets/smartphones? If so, out of curiosity, how often are you writing code on a smart phone/tablet? I've never written a line of any code on anything other than a laptop (when travelling) or desktop.
Ssh on a phone is better than no ssh, but good lord is it frustrating.
I would never willingly edit HTML (or anything else for machine consumption) on a phone, that's what real keyboards are for.