Torrent > DDL imo. If network is unstable DDL may break, you have to restart from scratch. Torrent avoids that by chunking into pieces. At most you'll have to redo a piece which is typically ~2MB less loss of data, far more stable. Also you don't get server side throttled like you do from most DDL sites.
That said, the advantage of DDL is if they have the file, the whole thing will be served. Unlike torrents where you can lack seeds and be stuck at 99% indefinitely. Pros and cons. But generally if I can, torrenting is the way to go..