I might be able to help you a little here. I have a Yamaha 2400is and a good friend of mine has a Honda 2000. We have both owned our respective units for about 8-10 years and they are used a fair amount as our main electrical source in our deer camp on private ground. We run them all night to power the furnace in cold weather. The Yamaha will run a 13500 AC but I did have trouble getting it to restart on a hot day when the AC compressor had pressure in it. The Honda will not run a 13500 AC in most instances...yes there are some exceptions.
As the previous posters have said, they are quiet and dependable, however, I have had more trouble with my Yamaha. Just this year, a bolt came loose on the generator portion and ruined it. It cost me about $400 for repair. Also, the Yamaha engine will start surging (hunting) from time to time and is usually correctable by adding a little seafoam to the gas. My friend's Honda has been bulletproof.
If I was going to buy again, it would be a Honda or two 2000's if for AC.