The battery switch shown is quite actually adequate for normal duty, I have a similar one installed differently. However if you want the best battery switch money can buy - look for one from Blue Sea Systems:
HD-Series Battery Switches - PN - Blue Sea Systems These also come in 2 way changeover and AFD options. Superb quality and sealed for marine use.
In the end how you install it is much more important than what it is. Don't add a new weak link to your cars higest power circuit.
Alan