I'm first time smoker. It's just me at home and money is an issue. I know to always go as big as you can afford. I'm hoping the #1 will be just fine for one guy.
A #1 will be great, you may just have to do some cutting before you smoke a few different things - like brisket and ribs, but it will do you well if that’s what you go for.
Like Jeremy said, the #1 will work great if you are willing to cut the ribs in half. I have done a 9# pork butt in mine. But a brisket would have to be folded or cut.