Generac. 8kw will do most unless you have a huge AC unit Ect. They are aBout 21-2400 plus 2000 to install i believe. They run on natural gas and are not terribly loud. They are not that hard to instal yourself either if you are electrically smart. Run your wire and power tie in with out back feeding into the pole!!, pour a concrete pad, tap into gas line, and a few odds and ends. After pad is ready, it's a 6-8hr instal I think my buddy said.
Most manufacturers require a certified electrician to inspect and then call into the manufacturer to activate a PIN to make the generator "live" and to start the warranty. Obviously this was done to keep from having your typical home handyman from installing the units falsely and risking injury to lineman. Most will void the warranty if not installed by an electrican.
Also an 8kW unit will not power a whole house panel. That is only 35 amps of 220 service.....not even an oven and the AC at the same time.
--Joe