I always use smalltalk when the problem would allow for it since I'm much more productive in smalltalk than anything else. It's great for certain random tasks - i.e. Want to set up a websocket server for some reason? Program it in smalltalk, test it interactively (literally debugging on execution errors, fixing and resuming execution until it works).

  If I'm writing a native windows app I'll go with dolphin smalltalk which imo is much nicer to work with and gives you a native gui.  I have to say though pharo is getting better all the time and has an active community.