SEO : long-term organic traffic can help consumers associate your brand with common queries within your niche. Effective for long term unconscious brand building.
Social Media: Being on the front of mind to your consumers in a place where they spend a lot of their time is always good. The one caveat is that most people use social media for leisure and being sold-to during that leisure time can be off-putting
Public relations: PR is a gold mine for branding if you can manage to find newsworthy content about your brand. Great for linkbuilding as well if you are a PR specialist with some SEO skills.
What else are some of your favorite methods?