I bought an Optima for my 300E because:
1) It is made by Johnson controls.
2) It has 980 MCA/750CCA.
3) It is completely sealed, nothing to leak, no corrosion issues.
4) It has a 24 month free replacement/72 mo prorate warranty (none of my sears Die Hard deluxe batteries ever lasted more than 5 years, and the prorate meant I was just getting a 15-20% discount if I accepted being locked into another DieHard. They all lost water during the summer, and they all developed corrosion on my Acura, Toyota, Honda, and 300E.)
5) It doesn't need a vent tube for Hydrogen gas. Several C class cars caught fire and MB had a recall because of improper vent tube installation. My next battery for the C230 will be an Optima for this reason.
6) It was a good fit, even as the red top. It is smaller and lighter than the MB/Interstate/DieHard battery, and by rotating it 180 degrees the cables all reached easily. It clamped securly in place.
7) It is replacable at any Interstate dealer, which is where I purchased the battery.
8) It was only $19 more than the 72 month warranty Interstate conventional battery designed for my 300E, and that battery had 50 less CCA.
9) It will work in any position, on its side or upside down. It is reassuring to know that if I roll the car, the radio will keep working!
:p