The registered user. The registered mark has been in use since June 2002 and has been registered since November, 2009 which would give the registered user a presumption of nationwide priority. If you've been using the name since before 2002, you may have limited rights to continue using it in your geographic area but that argument is muddied quite a bit by the fact that both of you are reaching a nationwide audience with your websites. The marks are identical and as you acknowledge, the services are the same. So, if we were a betting blog, we'd bet pretty heavily that the registered user could stop your use.
What should you do? The Dear Rich Staff thinks that the path of least resistance is to change your service mark and to notify the registered user that you are doing so. You can probably continue using the name for your LLC if you're just using it to sign contracts, write checks or for tax filings.