The answer depends on what you are looking at:
Let’s say, if you are looking at quick retrieval to active state from inactive / temporary suspended state, then Sleep mode is more effective, as all the data will be readily available in the RAM and hence there is no need to process data from the computers hard drive, which will be the case if the computer is ‘hibernating’.
If you are concerned about data safety, then it’s definitely the hibernate feature that stands first. The reason for this is, the data is written on to hard drive, rather than temporarily being stored on the RAM. The disadvantage of storing data on RAM is that the data will be lost in case of power outage or an accidental shut down. If the computer is in ‘Hibernate‘ mode then all the data and state of the running programs will be stored i hard drive, which will ensure that the data will not be lost even in case of power outage.