As an auto parts professional and a person who is versed in battery, starting, and charging (taking my ASE test in january) let me offer my opinion on the optima batteries:
Yellow Top - Designed to be completely discharged and recharged multiple times, made to run accessories, such as lights and winches and other accessories. Can be run in parallel with Red Top batteries on vehicles if need be, but recommended to be installed with an isolator.
Red Top - If you only have one battery in your vehicle this should be it. While not designed to be discharged as many times as the yellow tops, they usually are rated stronger and are designed to be the main battery in a vehicle system (takes care of starting duties).
Blue Top - Made for marine use. Has long discharge times and isn't recommended to be run in a vehicle. Basically this battery you completely discharge during use then recharge with a charger.
Cheers!