Looking for info on gen sets for my little house. Getting natural gas hooked up since they are waiving the install/construction fee.
House is all electric with well/septic so when power goes out I lose everything. I am not going to install generator but hiring a contractor.
I just want know what to look for? What brands to stay away from or get? Features needed or nice to have?

Everyone I know with a whole house generator has a Generac.
They do what they're supposed to do.
Just pick a brand that you have confidence will be around for the life of your generator in case you need support down the road.

Make sure there is enough gas pressure in your area to support a generator. Have your contractor put your data through his sizing program to find the correct kW rating you need.
Use a Service Entrance rated transfer switch so you don't accidentally back-feed your utility grid. Linemen have been killed when working on a line that is 'live' when it should be 'dead'.
Try to listen to various brands of generator in use to see if they are too loud for you.
Find out how much the maintenance plan costs and the service it provides.
Take a look at Kohler generators. They are well-built and made in the USA.

Generac headquarters is about 2 miles down the road from me. They have been there as long as I can remember so I'm sure they'll be there in the future. Kohler is up north and has been around forever as well.

I have a generac 11kw and it has been in service for a little over 11 years. I change the filters and oil annually, usually in the fall season. Never had any issues with it. Always starts and runs when needed.

We just moved to a house on an island. Has city water and gas but no sewer. Just had septic redone in Dec. Ouch. Anyway the house, built in 2000, has a 22KW Generac generator. SO NICE. A tad noisy but the central air muffles it Setup to start on the first Sat of the month to do a quick test and warm up. Have had the power go out like 3 times in 1-1/2 years and its GREAT not having to worry. Only bad thing is when the island loses power we dont get internet or cable TV (first world problems). Luckily the cell phoine tower is 1000ft away on the "main land") so I can cast Dave Chappelle from my phone.

Even though mine says Generac all over it, it also has Siemens on it too. If it's Siemens (German) it has to be good.

Residential gas pressure should be enough to run a generator but the proximity to the gas meter is critical. Long runs of pipe limit the KW rating of the generator.

Generac has a very good reputation around here in the inland northwest.
I went with a Harbor Freight 9000-watt gasoline unit that runs my place just fine.
Not as convenient as the automatic deals, but not a big problem for me.
But I don't use much electricity normally, and less when the generator has to supply power.

FWIW, when the utility company graced us with NG, they had to install a bigger commercial meter at my place.
My back shop is about 100' from the meter, which is 270' from the line in the road.
NG heats the front & back shops, and supplies house furnace, stove & clothes dryer.

While Generac has become a 'standard', the are not all they are cracked up to be. I have had two of their standby generators. First was an air cooled 12KW. It, along with 6 others within a couple miles of me, all blew up (and I mean blew-up) in a storm we had. Generac tried to use "Act of God" as the reason to not warranty any of them. After a long battle with them and lots of threats, they decided to give us all our money back for the units. Problem with them was that they had not planned for a quick temperature change in a high humidity environment (go figure...they are supposed to be a 'standby' unit for when there are extreme weather conditions). Inlets to the carbs apparently iced over from the humidity and rapid temperature changes. So, we investigated changing them to Liquid-Cooled versions. At the time, they offered a 20KW unit that was supposedly using a Mitsubishi based 4-cylinder engine. So, we figured that should at least be a worthwhile power plant with fewer issues. Until after got them and found out that they were a Mitsubishi KNOCK-OFF engine, made by Chery Motors based out of China. Immediately after installing them, started having issues with them Broken flywheels, starter failures (found out that the starters were essentially Ford V-10 engine starters and that by NOT using the Generac 'brand' starter, they actually did not fall apart), Radiator caps blew off (again, found out they were sourced to some Russian or Croatian company and made from cast pot metal that fractured). I still have my 20KW, but I still keep a standby generator (portable) for my standby generator (makes a whole bunch of sense....right?)

I have a buddy that just installed one of the Kohlers. Looked to be a very well built unit. Will have to see how that one holds up and functions. I installed a Briggs and Stratton 12KW air cooled at my parents almost 6 years ago. Seemed to be a well built unit. So far, zero issues with that generator.

Not a huge Generac fan. They are cheap (relatively speaking) and marketed as lifesavers.....not so sure I would agree. I would suggest you look around and do your homework. Lots of options out there.

I have been looking at Kohlers in the 10-12k range.
The 2 things I want during an outage is well pump and a/c(2 ton heat pump).Don't care about heat or lights.
My current generator is a portable7500W Generac works great except it won't start heat pump not enough starting amps.(i think it is called rol-loc amps?)
My neighborhood is a mix of houses from small like mine to mcmansions and most all the bigger homes have large 20k+ generators so I would think gas pressure would be fine. On the GAS LOAD SHEET they do want to know Gas Pressure Requested

While on the subject of back up generators, Anyone have any experience with a 3 point tractor powered unit? Having a 32HP Kubota and being all electric, I'm a bit leery of a gas or diesel powered Unit that may sit for long periods between uses. But a 3 pt unit I'm thinking could sit for long periods (inside storage) with no maintenance until needed

Its worth checking with your gas supplier. Where I am, they install two variants of gas meters. Depending on the size of generator, the smaller meter sometimes is not big enough for the house and generator. Worth the ask

don't forget to install a cutoff unit on the generator or house service box so it doesn't backfeed into the electric lines.
the electric company guys kind of frown on getting "bit" when working on the lines to restore power.

A Service Entrance transfer switch disconnects the house from the incoming utility. You can also accomplish this if you put a fused disconnect in the line coming from the utility pole to the breaker box in the house. You just have to remember to manually open the disconnect every time you run the generator. The Service Entrance transfer switch does this automatically.

A "manual" switch sounds like an accident waiting to happen. Do a legit install. Killing someone or yourself is not worth what you might save by a hillbilly installation.

I'm retiring in 20 days from the power company after 44 1/2 years. I'm very thankful to have been taught very early on as a young lineman to watch out for the Ding Dongs with rigged up generators. After the big ice storm right before Christmas in Tulsa, OK in 2007, one of said Ding Dongs dumbassed his disconnect procedure on his huge portable generator when we got the power to his street back on. He forgot to disconnect his generator before he flipped his main breaker back on. He was back feeding the panel with another breaker below the main. It went KABOOMYOW right in hs face, blew up his panel, backfed onto the energized power lines and burnt all of the backlot lines that fed his house and 9 others. After a week of being without power, they had to be out another night because we had to quit in time to drive back to NW Arkansas where our hotel rooms were. One of the lineman came over the radio and said "At least we will be able to get a truck to the pole tomorrow. His neighbors are gonna burn his house down tonight and we can back the bucket truck across the slab and reach the pole!"
Thank you to the OP, who intends to do it right!

They work very well. I Know a guy that has one. He has it set up on the 3 point and has a system to lower it on for log term use. Less wobble and vibrations. He says it works effortlessly . I believe he has a 25KW and his use is no where near that. He said its all self regulated so he just sets his rpm's at a certain RPM/HZ and the rest just plays in. He claims his Kubota only uses about one gallon every 4 hours.

Convert it to propane, This is an option for others where natural gas is not available. Just need a tank big enough for the usage.

Not sure what manual switch you are thinking of, but a properly installed and used one will only connect the house to the generator or to utility but not both at once. The only thing manual about it is that you have to throw the switch rather than pay a lot more for one that will throw it for you.

There are several ways to connect a manual switch. If not used properly, it creates a potentially deadly situation for others. It's not worth taking the chance that someone may not perform that one important step! Automatic switches are cheap, and in my county (maybe even state) they are mandatory.