I've only got experience with Haltech but so far it has been good. Currently have a Platinum sport 1000 in my car.
But regardless of which brand you pick you should also base your decision on the tuner you have in mind. No use buying a Haltech if there is no one that can tune it properly.
One thing I can recommend though is do it right the first time. With a properly tuned aftermarket ECU you will have better driveability and nicer power curve is my experience.