If it is value for money you are after, the Storm is the ECU for you. The Storm offers most of the advanced G4+ tuning features, at an extremely competitive price.
The Storm has more inputs (digital, analogue and temp), as well as more outputs than the Atom and Monsoon. Its 8 Injector drives and 8 ignition drives allows sequential injection and direct spark on engines up to 8 cylinders.
If it is Traction control, e-throttle or Peak and Hold injection you are after, consider an Xtreme or Fury.