It depends on a number of factors:
- Version selected: If you are using Milestone Corporate, I am presuming you'll use the high end for Avigilon as well - their Enterprise. Both of their MSRP licensing fees are in the similar $300 range
- Upgrade / software maintenance: Do you plan to upgrade the system over that period? Presuming yes, Milestone has an annual fee in the 15-20% of purchased price while Avigilon charges for individual major upgrades (like 4.x to 5.x)
- Analog cameras: Are you using encoders for analog cameras? Milestone recently matched / bested Avigilion's encoder licensing discount.
- Making a deal: How big is the system under consideration? 100 channels? 1000? more? The bigger it gets the more likely each company's reps will negotiate significant discounts to win the deal, e.g., Milestone might reduce maintenance costs, Avigilon might offer savings if you buy more of their hardware, etc.
Hope that helps to start. Let me know if you have feedback or can elaborate more on what the particulars are of the project you are looking at.
the Milestone SUP is not mandatory after the first year for Corporate, as well Device driver updates are free even without an SUP. Support is not tied to an SUP as well.