Canaries prefer a canary mix that includes a high proportion of plain canary seed (Phalaris canariensis) usually 40 - 75% of their seed mix. Canary seed is usefully for its high energy content, but it is very low in the most important breeding amino acids, methionine and lysine.
Canola Rape seed is typically 25 - 40% except in some countries where millet is used instead. Rape is an energy seed and lysine rich.
Millet is eaten best from sprays. It is helpful in weight control as canaries will not over eat millet. It is helpful because of its high level of methionine but it is lacking in lysine. In some mixes they may represent a third of the seeds. My birds love millet sprays but refuse to eat millet in mixes.
Oat groats are the richest natural source of lysine and the most important grain for breeding. Typically it represents about 10% of the seeds in a canary mix.
Sunflower (chips/hulled pieces) are very useful as they are rich in both methionine and lysine. Because of there high oil content, they are fattening.
Wheat provides the most balanced ratio of amino acids, especially lysine. It is feed soaked, sprouted or as cous cous.
Flax (linseed) should be fed as a small percentage (2%) of a seed mix as over consumption like other oily seeds such as thistle may irritate the bowl and cause loose dropping that cling to the vent and may cause potentially fatal plugging.