Choosing the right generator isn’t an easy task. Everything depends on you consumption. I’ll try to make it simple as follow:

Standby Generator ( Total Cost ~ $10,000 and up)

   Standby generator is connected directly to your electrical service. When you lose power from the grid the generator senses it and within ten’s of seconds it automatically turns on. This kind of generator can be connected as a whole house or partial for essential loads only. 

   Advantage:

• Automatically turns on when senses power outage,
• It can be sized up to your needs (residential ~10-24kW).

    Disadvantage:

• Expensive price for installation,
• Once a year maintenance.

Portable Generator ( Total Cost~$1,400-$2,000 )

   This kind of installation should be connected to the service manually. Same as standby generator it can be connected as whole house or dedicated circuits.

   Advantage:

• Less cost installation compared with standby generator,

    Disadvantage:

• Each time you loose power manually you have to interconnect the generator to the service,
• Limited power to 30A or 50A max,
• Fill up the gasoline tank each about 6-10 hours,
• Once a year maintenance (practically 2-3 years).

NOTE:

   This information is for reference only. From house to house is different, for example: some houses have electrical stove, electrical baseboard heating, heat pump or oil heating boiler…  To be honest I would say: the best installation is the one best suits your needs.