Masta Lifter pretty much hit it on the head...
If you are looking for mass...it's the deca.
If you are looking for the vascularity and extra stamina ...EQ
Both are "mild" drugs... but they have their very different properties.
Deca has always been a standard for mass-building in conjunction with Tests and D-bol (or Anadrol), while the EQ will increase red blood cell count, which increases vascularity and stamina because of the increased oxygen uptake to the cells from these extra red blood cells, but you must monitor your blood pressure while using EQ because it will increase blood pressure, sometimes significantly, if using other blood pressure increasing substances like Anadrol for example.
Both drugs have their place, and both are good for their respective tasks.
PS: It is true that EQ is mild, and it DOES take longer to see results while using it... sometimes 12 - 16 weeks or more...but it does a nice job at increasing vascularity if used in the amounts necessary... 600 - 800 mg/wk for the average 180 - 220 lb lifter. Many people simply do not run adequate length of cycle, and enough volume of the drug for it to be very effective.