I'm looking for a complete CO2 system with a solenoid valve, without the CO2
bottle/tank or a PH controller (yet ;-).

These three companies seem to be the "main stream" setups and are all
relatively close in terms of price. Are they relatively close in terms of
performance? Finding factual differentiation has proven fruitless. Is
chrome plating worthwhile considering the minor perceived cost increase?
Should I just shop based on price alone?

Are there other places I should look? Other brands or options to consider?

THANKS!
Sid