Yes, a GitHub profile is not perfect. It's way better than nothing - you get to see the developer's coding style, commenting approach and overall code organization. You say it's not your best work? then put something you're proud of on there before you send your resume. If you don't have one project that you think is representative of your current skill, you have to understand that is problematic for potential employers. Don't want to share it on GitHub? that's fine, send code examples instead of a GitHub link. But you can't hire a developer without reviewing some of his/her code first.

Personally, I find a Stack Overflow profile to be the best indicator of a developers skill, if he has a somewhat active profile (over 2-3k points). Being able to explain technical solutions, I think, is the best way to see if someone is both capable and can work in a team

Regarding resumes - another touchy matter. When I freelanced I haven't sent a resume as such as I had a portfolio site, but now that I'm on the other side of the table, going over resumes - most of them are completely terrible. Some people are completely clueless on what to put on a resume and others try to game it - putting stuff like "raised x metric by y% on project z" - giving me zero clue to what they actually did there. It's very rare I can get an actual glimpse to what the person was doing at his previous work. That's why you'll need to tell them your story when you interview... it's too easy to assume the interviewer was just lazy going over your resume because you think you "nailed" it, but in truth your resume probably sucks as an indicator of your actual experience and ability.