1--AEM---Best Out
2--VEC 2--works great, but it ain't the AEM
3--Split Second--works well for SC setup.
AEM, won't pass emissions, and is $2500 +/-, w/o tuning, and only a few and the proud can tune it in properly right now.
VEC2, $1000+/-, many out there that can tune it quickly and inexpensive
Split Second, $??, tuning similiar to VEC2