I used 3M 680 in the past but found it more difficult to cut than Oracal's 5600 (which also prints nicely). As for pricing, Oracal by a nose length. Never have problem with 5600 before. 'Always weeded fine (when I say fine, I mean fine for reflective... we all know what's all about). Oracal or 3M, very aggressive on adhesion. Both great products.
Never tried other brand. ...yes once: Avery. 'Will never again...