Side by side comparison of Payment Solution providers

When you chose one payment provider over another, what factors did you take into consideration?

Does anyone here have a side-by-side comparison that they created for themselves before making the decision? If yes, would you post it here in this thread for everyone to see, or email me directly at alex [at] nalem.com

Are you using more than one service? Which one(s)?

What are the pros/cons you have experienced?

Is there anything you wish they offered, which is currently not available with your current service?

Thanks in advance for your input.