For my needs inverter type portable generator is the best option that suits my needs:
I wanted to have a back up power that will be easy to live with and provide enough power for the essentials (fridge, gas heat blower, lights and electronic devices).
With natural gas heat, water and kitchen oven I do not need much electricity. So my choice was narrowed down to a ~2kW easy to carry with one hand and transport in a car inverter generator. Only Honda and Yamaha generators have build reputation of quality products there are many outside of Japan companies to enter the market but none of them have consistently good reputation of their products. I did a good research when choosing between the Blue and Red generators so I can share some key points and tips if you considering inverter generator or already narrow down you choice between the honda eu2000i and yamaha ef2000is.

First of all they are very similar generators at about the same specs and price - both are great choices.
Honda pioneered the portable generator market in 1960-s and have build solid reputation and support of their products. Yamaha entered the market after honda on and seems to have more aggressive marketing to compete with honda.

Honda is using 98.5 cc engine and Yamaha ef2000is has 79cc engine and thats what makes the main difference between the two - honda is two pounds heavier and can produce 2000W for half an hour (proven) while Yamaha arguably able to provide the claimed 2000W for 30 seconds. For most people it's not a big deal as they only need max power as surge power that is under 5 seconds for starting motors or other inductive loads. It is however needs to be taken in consideration if your equipment can use more than 1600W or your actual power output is compromised (high altitude, extreme weather, alternative fuels, improper maintenance)

The emission tests for 80cc engine in the same group as 100cc. Yamaha is better on emission ratings as well as time it holds emission ratings - 500 hours vs 250h of honda. At idle speeds yamaha is slightly quieter and consumes a bit less gas than honda but it's a bit louder at rated 1600W load and at max it is louder but not for long as it will give up producing the electric power and idle quietly to cool.

If you need more power Yamaha offers more options like 2400W generator and Honda jumps to 3000W or parallel kits. Yamaha offers really cool boost technology that uses battery to provide more power for a short period of time but currently it starts at their 3000W version. The yamaha2000 is a great choice if you don't need more than 1600W for some period of time. The smaller one thousand watt units are less popular for a reason, and many people prefer to have two smaller units running parallel then have one big unit that a single person cannot lift.

Honda has choke, fuel switch and pull cord on a side and electrical controls at front, yamaha controls all in one place.
Honda combines gasoline on/off valve and ignition switch. With yamaha you can shut the fuel off and burn the gasoline in carburetor dry - in honda there is a carburetor drain valve - please read the manual (you can get owners manual online for free).
Tip: Some honda users temporary unplug the engine stop switch (quick connector to the lower right of air filter with black and green wires) and shut the fuel valve to burn the fuel in carburetor and lines.
Honda's fuel pump makes it easy to add extended run fuel tank - Yamaha has no fuel pump on the other hand has a fuel gauge - very nice since it's has only 1 gallon tank.
Tip: If you have weight scales you can measure the weight of generator with and without fuel and use it as a fuel amount guide. If generator with oil but no gas 47.2 pounds with gas 53.4 then if it weights 50.3 pounds you are about half full (or empty)

Eu2000i has a "plastic" camshaft and a timing belt and 2000ef is a pushrod - it does not seem to make much difference but it's good to know - yamaha seem to be more reliable by design, while honda have a proven reputable history.

Yamaha comes with 12v dc charge cables and it's extra for honda - if you plan on using 12v changing cables keep in mind that its non regulated 8Amp (about one hundred watts) so using a proper 120v battery charger is advised.

One generator is traditionally red and another is blue - and that is about it as for the differences.

I choose the red one. I can manage to power the whole house (minus 240V items such as ac and dryer), used microwave without unplugging anything else - you do need to keep an eye what electricity is used on. It's very quiet, fuel efficient easy to operate and reliable. Pure sine wave power is also nice (even if most electronics can handle the ugly square AC there is no chance of damaging equipment if governour gets stuck like on conventional 3600RPM generators) also non inverter generator much louder heavier and often consume more gasoline on idle then inverter generator at full load.
If you can see that initial purchase price is not a big part of a quality of life panoramic picture - paying a bit more for a quality products can actually be cheaper in a long term.

Tip: you can get a "kill-a-watt" type meter to measure the power consumptions of household items (some items like cable boxes and playstations consume quite a bit when on stand-by while energystar should be less than 1 watt per item when not working but plugged in)
Also use kilowatt when running generator it gives you information on how much power is used as well as keeps track on how many hours the generator been working - very important for oil changes and other maintenance (generator does not have factory hour meter but it will blink on a start as many times as hundred hours it was used up to five blinks of 500+ hours - good to know if you looking at used generator with unknown hours)
Also as for oil changes I use an empty cocktail long neck plastic bottle that fits perfectly over the drain port and I tip over all oil straight into the bottle without spilling a drop on a drain lip of generator -no mess and easy - some people use short plastic pipe. 4-cycle oil is regular 10W-30 or 5W30 motor oil .4L
- synthetic is better, some people like to stretch to mobil1 0w-40 for air cooled engines.

The red plastic body of honda is relatively easy to scratch. When you removing the maintenance door you might want to put it outside on top to prevent from visible scratches.
Or if you reading this the mystery of scratched door panel should be more transparent.

I converted my eu2000i to also run on natural gas - really great option if you have natural gas in your house. So you dont have to go for fuel - the fuel comes to you. (or propane does not go bad over time)- no need for gasoline but still an option for traveling. With gasoline use fuel stabilizers (like StaBil) and drain the carburetor for storage.

Good luck with whatever you choose!

PS: Please research price and place of manufacture (some Hondas made in Tailand (not Japan)). Yamaha outsources to China . At the time of purchase the generator was not available from Amazon but I choose my seller wisely.

These things rock! This is my second, added to parallel with my four year old example to run my r/v air conditioner. Two of these in parallel are lighter and more powerful than an eu3000i, and you can only use one for lighter loads. Super dependable, clean inverter power, lightweight, easy to service, and whisper quiet.... You get what you pay for with these. Details like the carb drain, 12v output, easy parallel operation, and QUIET, make the difference.

For the few naysayers out there...

1.) RTFM
2.) These are quiet when compared to generators, not toasters... They still make noise, just far less than others.
3.) Use 89+ gas with no more than 10% ethanol. Do not use e85, or other fuels containing more than 10% alcohol. Gas is not gas... read the pump labels. Use a brand-name fuel stabilizer. I like Sea Foam, there are others.
4.) Unless you know you're using it in the next few days, like on a multi-day camping trip or boat voyage, DRAIN THE CARB. It takes five seconds and I've used my two examples for hundreds of hours with periods of no-use ranging from a week to 4 months. This is with E10 91+ fuel and 1 oz./gal of Sea Foam added.
5.) If you're going to use it very infrequently, consider a canned enthanol-free gas like VP-SEF, or TruFuel. These can last years in the can. They're expensive, but you aren't using much. If you use the unit for an extended period and add pump gas, drain the fuel and replace with canned gas before you store it again. Even with canned fuel, DRAIN THE CARB.

See a pattern here? Maybe related to fuel? During the racing season, I use my units 10-12 hours a week and change the oil monthly with Mobil 1 synthetic. The unit only holds 13 oz. of oil, so oil cost really doesn't matter.

Read and follow the manual and this thing will outlast you... My older unit has hundreds of hours of use and runs as well as it did the day I unpacked it.