Assuming you did the math right on your retail gas & electricity rates the ATI-66 is located in a garage or something you'll probably better off with the ATI-66.
If it's located inside of conditioned space and not taking it's heat from outdoor air, half the heat is coming from your heating system, and in Portand's 8-9 month heating season that's an additional cost that doesn't show up on the power use of the water heater.
AirGenerate is a small TX startup (manufacturing is in China) but has been around for more than 5 years, and has sold tens of thousands of their retrofit heat pump units that hang on the top of standard electric ho water heaters. The ATI-xx units are among the highest efficiency heat pump water heaters in the industry, but on a 2012 in-situ field monitoring study for the NEEA on early revision ATI-66 there was more than a 10 % early failure rate (3 out of 28 units.) The warranty is good, and the stainless steel construction should give it a 20+ year lifecycle, but pay attention to it's behavior in the first year or so. If it starts running 24+ hour heating cycles on a regular basis it may need to be checked out.
Navien is a Korean company (Kyung Dong Boiler) that has been around for decades. Their north American support is a bit spotty, and their quality control isn't quite up to the levels of the big Japanese vendors, so if you're going that route be sure this isn't the contractor's first tankless installation, and hopefully they've taken the distributor/factory training from at least SOME tankless HW heater vendor. Installed by competent installers most will do just fine, but in the event that there are any issues with it you want the installer somebody who isn't a clueless newbie on the job.