Rogue question sub+

Okay so basically I was wondering something.
I know alot of factors come into play when trying to calculate rogue dmg. I was trying to figure out which dagger would get me the highest ambushes.
For example Wrath glad's shanker's dmg is - "326-490", while bloodsipper's dmg is -"285-531".
So my question here is: Is the second number more important, therefore when equiping bloodsipper i will see an incrase of my rogue's damage from lets say 1060-1230 to something like 11XX- 13XX or will wrath glad's shanker net me more dmg therefore higher ambushes because of the first number.
Couldnt really find any 3.3.5 SUB rogue spreadsheets and didnt wanna buy one just to realise i failed.

The only thing that matters is the dps and attributes man. The numbers only tell us that the Bloodsippers damage is more spread. It can do higher but also lower damage than the wrathful dagger. But both net an average of 408 damage.(285+531)/2=408=(326+490)/2. Altough because of its higher attackpower Bloodsipper will ofc give more dps in the end.