I am speaking not as the guy who designs and sells closed sourced widebands @ 14point7.com, but as the guy who made the open source wideband SLC Free,
viewtopic.php?f=16&t=2083
This is my personal experience with other brands of lambda controllers
Innovate LC1- Tested 1 unit. It is accurate and fast, uses a mix of commercial and industrial grade components. Sensor life is very short and requires constant calibration. I believe the issue with the LC1 is that it does not properly detect the sensor temperature and that is the source of most of it's problems. Has over voltage and reverse polarity protection but no fuse. Uses their own uC + firmware for lambda control. Uses Bosch 4.2
PLX SM AFR- Tested 1 unit. It is accurate and fast, uses a mix of commercial and industrial grade components, creates alot of heat which is problematic since the DACs they use is commercial temperature grade. Uses low end electrolytics, which again is a big problem due to the high heat output of the unit. Has absolutely no protection on the power supply, no over voltage, no fuse, no reverse polarity protection. Uses their own uC + firmware for lambda control. Uses Bosch 4.2
BPSX- tested 3 units, It is not a wideband, I do not know what it is, but you are better off with a narrowband sensor + narrowband gauge. Uses their own uC + firmware for lambda control/miscontrol. Uses Bosch 4.2
NTK AFX + NTK sensor- tested 1 unit, very well built, has good protection circuitry, I believe they use all industrial grade components. When tested with 11.78 AFR test gas, the unit read bout 0.5 AFR richer, both the unit and sensor was brand new. Uses NTK ASICs for lambda control. Uses NTK lambda sensor
AEM (the one that is a gauge)- tested 1 unit (unit was used, sensor was brand new). I do not recall the internals but I also do not recall being impressed or dissapointed with it so the internals must be around average. Tested with 11.78 AFR gas, the unit read 0.5 AFR richer, the unit was used but the sensor was brand new. Uses Bosch ASICs for lambda control. Uses the Bosch 4.2
Glowshift/Prosport- test 2 units, both units were new with new sensor. Internals are good, uses industrial grade components, has proper voltage protection. When tested with 11.78 test gas both units read about 1 AFR richer. Uses Bosch ASICs for lambda control. Uses the Bosch 4.9
Tech edge 2Y1- Accurate, very slow. Internals are good, industrial temperature components, has proper voltage protection. Uses their own uC + firmware lambda control. I tested it with the Bosch 4.2, 4.9 is also supported but I have not tested.
Tech edge 2J2- Accurate, very slow. Internals are good, industrial temperature components, has proper voltage protection. Uses their own uC + firmware lambda control. I tested it with the Bosch 4.2, 4.9 is also supported but I have not tested.
Overall the most accurate units tend to use controllers developed from scratch, ie do not rely on Bosch/NTK Asics.
My personal criteria in order of importance is; accuracy, reliability, and then response time. If my 14point7 controllers are not available, I would reccommend Techedge units, after that it is a tie between Innovate and PLX. I personally dislike the owner of techedge, so I am not playing favorites by putting Techedge above the rest of the competition.