I use my AA account solely as a backup. But if you have a long-term goal of earning lifetime elite status on AA (1 million miles for gold, 2 million for platinum), earnings from partner transfers such as DC counts toward qualification, making an AA transfer just slightly more valuable in such circumstances.

Each person's view of "most value" will depend on the intended use of the miles or points. I value the flexibility of keeping all my accounts "alive" every three years if necessary by adding 1000 miles from DC, and for my family, too (except for AA & BA).