What's the best wild-bird seed to avoid waste and filler?

Reviewers on r/birdfeeding and r/Ornithology consistently recommend no-mess, shell-free blends and warn against mixes heavy in milo, cracked corn, or artificially scented seed. Within the candidate pool, blends featuring black oil sunflower, peanuts, and safflower drew the most positive verified-purchase feedback, while cherry-scented mixes drew mixed reactions.