I posed the following question on Twitter, and thought the answers might be helpful to others (as well as a place to archive further discussion that's actually searchable :P).
Here were some of the more detailed responses. This is a wiki, so feel free to add additional ones, either in the post or comments!
By popular vote, the people who responded by far favoured Omega. Here were some things people said about it:
- @karschp responds, I haven't done too much, but I've played with Omega a bit and it seems pretty awesome.
- @michaelschutz responds, Experimenting with Omega for responsive work. I think it's a fantastic base theme.
- @valariems responds, just downloaded #omega tonight, and very impressed. Responsive design built in. Can't wait to play with this more.
[Edit: The twitter comments directly below apply to the old Zen 7.x-3.x release and not to the new HTML5/responsive/mobile-first Zen 7.x-5.x release.]
Zen also makes a strong showing, although not too many people seemed that excited about it. :)
- @dserrato responds, I recently did a responsive design and I started with Zen.
- @jeff_shamley responds, using Zen for now, though its not optimal. Omega seems to have the lionshare now. #drupal
- @aveldina responds, we use Zen. It's not responsive out of the box, but excellent to work with. Haven't fully tried Omega yet, but it looks promising!
- @epersonae responds, since I started w/Zen, I've been trying to shoehorn into that, so far not super-successful. (will be coming back to it later.)
- @jpamental respnonds, started with a zen starter theme and built up with html5 boilerplate, respond.js and other bits ( #responsivedesign )
However, there were also a lot of people who recommended against the idea of a base theme at all:
- @canarymason responds, Start from scratch, and fold what I can into my http://drupal.org/project/survivalkit theme. Doing responsive right involves a lot of custom work IMO, so I don't rely on any tools (theme or framework) to do it for me.
- @tmplunkett responds, http://drupal.org/project/basic, or start from scratch.
- @maerys responds, start with an adapted theme based on the skeleton boilerplate. http://www.getskeleton.com/
- @kevincrafts responds, making my own based off 960.gs
- @rupl responds, so far each case has been unique enough to start fresh. Too much baggage in most themes.
There were a lot of varied answers to this question, as well, including lots of theme names I'd never heard of before. Might be worth checking into some of these if Omega doesn't suit your style:
- @funnymonkey responds, For responsive design, Terrain. http://drupal.org/project/terrain #drupal Based on Hexagon: http://drupal.org/project/hexagon
- @adamdicarlo responds, there's Doune, too, which uses Skeleton but adds push & pull classes, and integrates with Context Layouts #shamelessplug
- @knowprose responds, I typically start with Mayo for l&f with the client and tailor another theme as needed.
- @jonathansousa responds, Starting with HTML5 Base since I'm mixing #ResponsiveWebDesign and #HTML5
- @drupleg responds, Omega on 6 of my sites so far, but also playing with #drupal Stark theme and this Boilerplate - getskeleton.com
- @shlidor responds, We now use
965Sasson as a starter theme for all of our projects.
- Laura Scott has a blog post about her Square Grid theme, which uses the Square Grid CSS framework.
- Start with a published subtheme. Sky gets some votes. You start with something closer to what you want and your learn about the base theme by example.
Here are other themes added by folks in this thread.
Just released in beta is the new Adaptivetheme 7.x-2.x version with full mobile support - it does responsive and adaptive layouts out of the box and allows you to configure layouts, widths etc for various screen sizes. The theme uses respond.js to parse the generated CSS file that holds the media queries for easy support of IE. You can view a short intro video on responsive layouts in Adaptivetheme 7.x-2.x.
The theme ships with a blank starter theme with sensible default media queries and layouts for each device (standard, tablet, smartphone), and there are three styled sub-themes you can download and try and/or modify to suite your purpose: Sky, Pixture Reloaded and Corolla (7.x-2.x versions respectively).
The 7.x-2.x responsive version of Adaptivetheme was brand new when this was published so I'm putting in here because I know its rock solid with years of development behind it and powers something like 7500 sites already, and the media queries driven layout engine is simply an evolution of the framework and well worth taking a look at. / Jeff Burnz