At the moment, my primary language of choice is Groovy. Second to that, Java.<p>If I'm using anything else, it's probably chosen because it's purpose specific in some way (like using Prolog for logic programming or R for statistics, etc.).<p>We're not really doing anything that uses a desktop UI interface (ie, it's all web based) but I have some ideas for some things we may do later that we might build on top of SWT (Eclipse).
I've used QT mostly. We use it because all of our code is C++ and so is QT. Also the documentation is among the best I have seen and there are some great books on the topic.
My interest is:
* A portable programming framework including UI
* The portability includes being portable to Android
* Already has a large base of open source code written in it<p>The framework that satisfied all these conditions was Simple DirectMedia Layer, version 1.2. Cross-platform games and applications which have been in development for over a decade can be ported with incredible ease to Android.<p>I have a particular focus on Android though, so your needs may be different in other cases.