The Champion inverter is about half the price of the Yamaha 3000, gives you 100 more watts, which can help with the inrush current from your A/C, and is by a brand with a reputation.
Comparing it to a Yamaha iSE:
It has a 1.59 gallon gas tank, compared to the Yammy's 3+ gallon, so expect about 4-6 hours at half load run time.
It weighs almost 1/2 as much as the Yamaha.
It puts out 100 more watts.
It is manual start, no way to upfit a remote to it.
Pretty much, if you don't mind the smaller fuel tank and the manual start for something that is half the price, it is a good generator. Were I buying a 3000 watt generator again with that Champion offering on the market, it would be a tough choice between the two, although any 3000 watt generator will have a tough time starting a 15,000 BTU AC other than the Yamaha 3000iSEB with the battery that can give 500 extra watts for eight seconds.