At work we use VisualAge for Smalltalk. At home I use VisualWorks. I'm in general leaning towards VisualWorks as my preferred Smalltalk these days for a number of reasons. I think the team is very open, from the technical side to the product manager side of things and the community is also very open. VAST has much of the same and in general both code bases have very high quality code, so I couldn't pit one against the other way way - in fact, I once tried too.
When I first began writing code with VW I started to do a write-up of what's better and what's worse in VW. As it turns out, the two biggest issues I had with VW were the debuggeer and the lack of ENVY. The debugger has since surpassed VAST with VisualAge Assist's debugger. As for StORE, well, lets just say the reason I liked ENVY so much was because I've written a heap of tools on top of the ENVY paradigm that make group development a breeze.
One such tool is the Image Syncer. This little beasty runs in everybody's image and listens for changes to the code base, loaded code from ENVY, removed methods, etc.. all the usual operations. From there, you nominate a 'Sync Point'. This is a directory which is usually a shared directory on a machine. You can actually have many sync points.
Then each image reads from that directory any other image's contents and loads up whatever differs in to its own image. After doing that it then writes out its own changes to the directory. It dawned on me the other night that the solution we've come up with is very similar to OSPF's superiority over RIP, simply by having an agreed upon place to publish changes to the 'code topology'.
If there are any VAST developers out there who are now salivating at the idea of having 6+ computers constantly sharing the same coded base, your waiting will be over soon, as Wizard Information Services is planning to make a public domain release of many of our utilities - including the Image Syncer.