I've heard bad things about almost ever Red Sea product. Basically rated as low end.
I use Aquarium Pharmacueticals, Doc Wellfish. It's what my LFS uses. I was gifted a "professional" kit, comes in a nice tackle box, as a gift for being a great customer.
My other LFS uses Tetra.
The kits that I hear are the best and most accurate are, in order, Salifert and SeaChem. They are also pricey and do not offer kits.