Lexol makes an excellent product. They've put alot of time and research into all three (Cleaner, Conditioner, Vinylex). They don't make products besides these so they focus all their attention on vinyl, rubber, and leather care products.
I've found that Lexol is a mild cleaner and is best used on a nearly new, lightly soiled interior. To completely clean grubby leather it might take a few applications. But to clean and maintain new leather, its excellent.
Leatherique is best known as a leather "restorer"; more for neglected leather than anything else. I'm sure their products work well.
I've had excellent results from Eagle One's leather care products. A more powerful cleaner than Lexol but very effective. Also,
Pinnacle's leather care products work very well too.
Maybe the best thing about Lexol is its excellent availability at retail. Eagle One is also pretty good but the other two are mostly mail order only.