I really like the deluxe seed mix from LadyGouldian.com, an online finch supply store.
Many of you may have noticed that your birds prefer different types of seed during the different cycles they go through each year…Breeding, Resting and Molting. By adding additional seed types to this mix your birds have a wider variety of choices, which is a healthier diet all around. This NEW...
ladygouldian.com
It has a lot of good seeds at a good price. My birds like it and leave nothing behind. I have finches, parakeets, and quail.
I also like the mixes offered by Glamorous Gouldians. They are more expensive, so I offer them less often, as a special treat or during molting or just for a bit of variety.
Millet Mix/Lady Gouldian Finch Breeding Diet/Gouldian Finch Food/Lady Gouldian Finch Supplies
Premium Herb Seed Mix for Breeding Lady Gouldian Finches - Rye Grass Switch Grass Hemp White Perilla Rape White Lettuce Black Lettuce Blue Poppy - Glamorous Gouldians
glamgouldians.com
I like these seed mixes quite a bit and I think they are very high quality. But my budgies' base diet is Roudybush pellets, not seeds. A good pellet will provide a better nutritional profile than any seed mix.
I don't mix pellets and seeds - I feed separately, so I can control how much seed is available each day. Otherwise, I think my birds would over-indulge and eat too many seeds. Instead, they get free access to pellets 24/7 and a measured portion of seeds, usually scattered around the aviary in various shallow dishes or trays. I also find that there is a lot of waste with many seed mixes that add too much filler, like bits of dried carrots that my birds never touch. I prefer sticking with true seed mixes that don't add a lot of extras. Just seed.