What is good delegation service

Trust

A good delegation service is first of all trusted.

If you delegate your baking rights the reward will be distributed to the baker (in this case the delegation service.

The provider has to send the baking reward (minus the applied fee) back to you. That means that you have to trust the delegation service.

Fees

Every delegation service takes a fee for its service. Choose the delegation service with the best fee structure for you.

Overdelegation

Depending on the service's baking bond (amount of Tezos he is actually baking with) the delegation service can accept only a limited amount of Tez via delegation.

Overdelegated delegation services will not receive rewards for the overdelegated amount of Tez.