I’ve been using the SharePoint extensions for Visual Studio 2005/2008 for several months now, and after recently having a chance to see how some of the other tools work (WSPBuilder, STSDev, etc) I can safely say I like the extensions best. The other tools do some great things, but they both assume you’re using C#, and all my SharePoint stuff is done in VB.NET.
Version 1.2 for Visual Studio 2005 was OK, but wasn’t as easy to work with as the superior version 1.3 for Visual Studio 2008. I haven’t seen any of the betas for Visual Studio 2010, but I’m hoping the built-in SharePoint tools they’ve created will be even easier to use.