I draw a lot of UML diagrams, but I don't use CASE tools. The reason is that I'm interested in UmlAsSketch, not in all the repository stuff. So far my regular choice has been Visio. Although Visio comes with UML templates I don't use the built in ones - I prefer those of Pavel Hruby.
Visio has worked very well for me, and it's still my first choice. But I'll admit to a wandering eye. Visio only works on Windows - and I also use Macs and Unixen, so it would be nice to have a tool that worked on all (or actually a common data format). I like to collaborate with others, so something open source would allow them to draw diagrams if they don't have access to Visio.
I've played a little with OmniGraffle on my Mac, not enough to really evaluate its capabilities - although it does produce lovely looking anti-aliased output. UMLet is an interesting looking project too.
The biggest thing I would like however is to specify my UML diagrams as text. That may sound strange - after all UML diagrams are diagrams, so why use text? Text has some advantages. Much of diagram layout is tedious to fiddle with in diagrammatic form, and would be much easier to do textually - using the diagrams as a visualization rather than an editing mechanism. Also text formats allow you to easily track changes over time with cvs and diff.
As a result I was intrigued by UmlGraph. The part of this that most grabs me is the sequence diagram editor which uses the venerable pic program. This page shows show the pic macros create a nice textual representation of a sequence diagram. Of course there are some limitations of what you can do in a pic macro and I can imagine a textual representation that's even more compact and clear.
objects thread, t:thread tool, :Toolkit peer, p:Peer, unborn trace found: a1:run(3) -> thread: run() -> tool: callbackLoop() -> self create -> peer handleExpose() -> peer: return delete -> peer
That's just off the top of my head. I don't know how well that would really work in practice. In any case I intend to experiment with UmlGraph as it stands to see how it would work for me. The pic program is so small I could easily tweak it if I wanted some changes.
UmlGraph's class diagram generator is nice in that it can produce stuff from Java source files. However for just a diagram syntax it looks rather awkward - and I would like some control over placement of classes. Enough to say Customer is to the left of Order. So perhaps represent this diagram with something like this:
layout row: Controller, EmbeddedAgent, URLStreamHandler, ChannelIterator SetTopController below: URLStreamHandler PowerManager below: SetTopController interface URLStreamHander operations OpenConnection() parseURL() setURL() toExternalForm() class SetTopController specializes Controller EmbeddedAgent implements URLStreamHandler attributes authorizationLevel operations startUp() shutDown() connect() associations -> PowerManager class ChannelIterator dependencies -> SetTopController keyword:friend
Again this is just off the top of my head. The important thing is that I'm glad to see someone going in this direction - and would like to see more.
Here's some similar sketch-like tools that people have told me about