The choice was between the FAST XFI 2.0 and the Megasquirt 3x for me. The two systems nearly match each other in features, while the FAST XFI cost ~$3000, and the MS3x cost ~$1200-1800 for me (the base unit is like $650 from DIY, but you need a number of other things to "complete" the kit for comparing it to the XFI).
For those who are interested, here is a comparison put together by Matt Creamer at DIYautotune (check out their dragpak chally on youtube):