There is no real favorite for weapon enchants but in my opinion it mainly comes down to Mongoose vs. Blood Draining, the reason for this is that all Blade Warding adds is avoidance and it has a lower uptime than Mongoose.
In Mongoose vs. Blood Draining it comes down to would you rather have a little bit of armor, a little bit of avoidance and a little threat or would you rather have a few smart heals. I prefer Mongoose because of it's overall consistency and that in current content most of the time that small heal from Blood Draining. There has already been some big threads on this subject http://www.tankspot.com/forums/f97/5...-draining.html