I used WSPBuilder since the early releases where it was just a console app.
For a period i used STSDEV, but after seeing what Keutmann has done with VS integration and all, im growing really fond of WSPBuilder again.
Sure it has its quirks (like adding all worker processes when debugging, re-building up to date solutions before building WSP file, OOTB templates using old webpart namespace, inability to add assemblies to wsp packages if file is in GAC etc) but for a guy like me that works with SharePoint in Visual Studio every day, its a great tool that makes me blissfully ignorant of DDF files and pesky manifest files (and yes i do advocate that you first build your first 100 WSP files manually so that you know what goes on behind the hood, but after that its just a nuisance).
On the downside WSPBuilder documentation is non existing and you have to rely on Codeplex forum or blog posts like the recent one by Zimmergren that Wictor mentions. Hence im sure lots of the above quirks can be configured away, but it takes alot of digging to find out how (like you have to know that if you want to deploy assemblies in same project to both GAC and BIN you need to have folders called GAC and 80/bin in root of project, and not configure anything in wspbuilder.config.exe)
I do use VSeWSS 1.3 but only for extracting site or list manifests (i do this less and less btw since theres lots of nice STSADM extensions out there that does a better job than VSeWSS).
What im extremely curious about, is how the OOTB VS tools for Rosario and 2010 will be. Nightmare scenario would be a VSeWSS 1.something...
STSDEV is good, but limits my freedom of doing "business as usual" in VS. Also i cant remember when it was updated last time...
[edit: im not an expert in these things, but isnt questions like this normally marked as community wiki?]