You are not alone. This winter has been mighty tough on the eastern part of North America.
I have not worked with Kohler generators for many years but found them to be very good products. Their off shore built portables are another story altogether.
The Guardian standbys are attractively priced but the quality is a bit wanting. The cabinets could be a little heavier and the electronics a little less trouble prone. IMHO Briggs and Stratton make a better unit but come at a price. However the Empower 7kw and 10kw models are rather noisy being equipped with single cylinder engines. The 12kw and up air cooled have twins and are much quieter.
Regardless of the brand you choose, go with a dealer who knows how to properly install and service the unit. This is really important. Talk to neighbors who have standbys to learn from their experience. A lot of sellers are in it for the initial sale and disappear when problems arise. It is not a plug and play. If you hire your own contractor, make sure he and the gas fitter are familiar with the product. We see a lot of problems with mismatched transfer panels and gas regulators.

Check with your natural gas supplier if your service
can supply the volume and pressure required by the
unit you are interested in.