Savagery Provides the best possible sustained (raw)DPS out of all enchants (PvE)
Agility gives you 1.4% more crit over Savagery, at the cost of 19 weapon damage.
Mongoose fails miserably on a slow weapon like DT. The proc rate grants 30 agility (1.2% crit) and 5.25% haste on average. Seems nice, but it's too streaky to rely on in PvP, and Savagery outperforms it in PvE.