I've always liked the branding of First Direct. They are an online and telephone bank. They haven't changed their logo or branding for over 20 years and for me that is a good thing.
With their emphasis on clear typeography, using the Helvetica font, they manage to convey a solid outward appearance. Although they change the website regularly. They ran an interactive home page over Christmas, where customers could create their own message over a frosted effect on the home page. Overall, they are a no-nonsense bank with a no-nonsense brand.