I prefer Olivia's myself, but as long as you keep it in a cool, dark place it should be fine. I keep mine in the fridge when not in use and I run warm water over the bottle before use.
My advice is to buy small bottles of different brands and find which one you like best. It's often a matter of personal preference. What method of cloning and in what medium are you using? If it's soil, Olivia's Gel and Solution is the shit but I hear great things about rootech gel as well.
Just remember to separate the gel you will use from the bottle, contamination the bottle wastes money and breeds BIG problems. Shot glasses are great for that. They are cheap, easy to clean and won't tip over easily.