The automatic backup generator option is the premium choice as it eliminates any manual action when the power goes out.  When the power goes out the backup generator will automatically start and the automatic transfer switch will switch the power source to the generator.  When the power comes back on the transfer switch will detect it and transfer back to the main power source turning off the generator. The system and the generator can be sized to power the whole house or critical circuits.  This setup requires a permanent concrete pad to house an all weather generator setup.  Ideally a gas line can be run to the generator to provide a steady fuel source.    

Items required:

• An all weather generator with housing
• Concrete pad
• Trenching for gas line and electrical wires
• Properly sized automatic transfer switch

Items that influence is the distance the generator is from the main panel and the size of the generator.  Other things to be aware of is to have some routing servicing contract with a generator servicing company

Another option is to replace the generator with a battery backup.  This will take some space in the house but will not require a pad and a trench for electrical and gas connections.  This option will provide less power for a long power outage but doesn't require yearly servicing.