A service contract is a promise with conditions attached. Before you compare any two of them, or compare one with the manufacturer's own terms, put the same questions to each. The answers are in the contract text, and the sales conversation is not a substitute for that text.
Who stands behind the promise
Ask who issues the contract, who administers claims, and who pays the repair facility. Some contracts come from the manufacturer or its affiliate, and others come from a separate company that sells them. Ask for the legal name of the company that will answer a claim, and write it down. Nothing on this page means that any claim will be paid under any contract.
When the clock starts
Find the waiting period. A waiting period is a stretch after the contract begins during which claims are not accepted, and it is often measured in time or distance. Ask whether it applies to every item in the contract, whether it restarts after a repair, and whether the factory warranty is still in force during it.
What the exclusions list says
Read the exclusions as a whole, not as a summary. Ask the seller to show you where the contract treats wear items, cosmetic parts, damage from neglect, and modifications. Check whether the list refers to outside documents you have not been given. If it does, ask for them before you decide.
How a claim is paid
Ask whether the shop is paid directly or whether you pay first and request reimbursement. Ask whether a deductible applies and where it is stated in the text, and whether the repair facility can be any licensed shop or only those in a network. Ask what steps a transfer to a later owner requires and who completes them.
Compare with the factory terms
A service contract is easier to judge once you know what the factory warranty already covers and when it ends. The brand pages on this site describe factory terms, when they end, and what a contract adds, for the makes listed there: Acura service contracts and Audi service contracts. Use them to frame your questions, then check every answer against the contract you are actually offered.