If you can swing the cash, I would say to go with an Optima. I used to have a standard battery in the VX and the posts and cables kept corroding. I had to constantly clean them off, and the corrosion ate into the heat/sound mat on the underside of the hood. Since I installled the Optima I haven't had any corrosion problems. The Optima's are sealed so they can be mounted in any position and have a high vibration resistance.
I know they're expensive, but in my opinion, they're worth the price.