It all depends on how much control you want.
The Tec-II can either be used standalone or with the stock ECU in place.
The Haltec is a standalone unit. There is also the Motec, Link, or even the Pectel.
Link and Motec are both bringing out new versions of their ECU's.
I believe the new Link is a generic ECU (which is meant to be on par with the Motec, but cheaper) that requires a short adaptor loom to convert from the stock ECU connectors to the Motec connector.
The Pectel units are very high end (possibly more advanced that the Motec). They require a new crank sensor and a few other mods to get them working.
It all depends on your budget and how much control/features you require.
The Tec-II is a very good system and has been proven to work very well.