Aftermarket air conditioning

I've been shopping for one of the aftermarket air conditioning kits, but can't decide which one to get.

There's the "Perfect Fit" series made by 'Classic Auto Air', and then there's the "Sure Fit" series made by 'Vintage Air'. Both companies gave me the exact same sales pitch and the same answers to my questions.

Both kits are application-specific and have the same relative price tag. Half the Mustang shops I go to use only one supplier, and the other half use only the other supplier...

Anyone have any good / bad experience or advice on good aftermarket A/C suppliers?
[addsig]