David Co's Evernote
I've tried TSW and a few other Evernote implementations, and also looked at detail in the DAC Evernote implementation (and was one of the reviewers). Interestingly enough I actually have my own customised implementation primarily because I really wanted each project to have a separate notebook (so I could create 'project files').
My recommendation after all that is to start with the DAC implementation. It really is the simplest, most straightforward option to get your started GTD'ing in Evernote. You can always tweak after that if you find you have a different style anyway!
I wouldn't change to another tool - Evernote as my list manager and part of my reference system works so so well.
Agreed, you can also use the Evernote voice note feature instead of Siri in the future.