A few things you should look for when purchasing a Vehicle Extended Service Care policy (VSC):
1. Who backs the coverage? One's that are backed by either the manufacturer or an A-rated or above insurance company ONLY!!!
2. Look for "Exclusionary Coverage". These policies will have a list of items that they DO NOT cover. With a vehicle like the MB, a "Named Component Coverage" won't do you a lot of good as a majority of the "high tech" components will not be listed.
3. When does the policy become effective? Does it back-date to the original Vehicle in service date or from today forward?
4. The most important thing...Does YOUR MB mechanic accept the warranty? Before purchasing a VSC for your vehicle, be sure your mechanic will accept it. Also, you need to check to see how the VSC company pays the bill, ie, Do they pay with a check or with a credit card or do you have to pay for the repairs and get reimbursed?
These are a few of the more important issues to be aware of. Now to answer your question, I would either go with the Mercedes Plan or with AON Warranty Group. AON is one of the oldest companies in the VSC industry and they pay their bills. Not sure how the prices compare, but with either of those you would be fine.