We have a portable generator and a transfer switch set up on the fuse panel. This keeps the fridge, upright freezer, HVAC, hot tub (needs to not freeze in winter), modem (though typically if power is down internet also down) and several lights on the first floor running and I don't have to run cords all over the place. We also have 2 natural gas fireplaces that can run if the HVAC is out.
I keep a lot of shelf-stable pantry staples stocked like rice and beans. Upright freezer usually fairly stocked.
Propane tank for grill. Stove is natural gas so that works during power outage too.
About 6 gas cans are kept mostly stocked. The standard selection of flashlights and candles.
The longest we had lost power here was about 6 days. It was March so it was still cold so at that point it's mostly about keeping the house at a reasonable temp.
For a more prepper type mentality, our property has a large creek and I have considered stocking the house with Life Straws and other products that make water drinkable but I haven't gotten them just yet. Firearms on hand. We already have lots of camping supplies, hatchets and other manual tools.