Which tankless water heater brand is the most reliable?

Which tankless water heater brand is the most reliable is often considered to be Rinnai, Navien, and Noritz, with Rinnai frequently ranked top by plumbers and consumer reports for fewest callbacks and long lifespan. Rinnai Corporation, founded in 1920 in Nagoya, Japan, headquartered in Nagoya, Japan, with factory in Griffin, Georgia, USA, makes Rinnai tankless water heaters that average 4.6 to 4.7 stars, with reliability praised for 20 plus years lifespan, 12-year heat exchanger warranty, and few failures, with plumber surveys ranking it top for reliability. Navien, founded in 1978 in South Korea, headquartered in Seoul, South Korea, is also considered highly reliable, with 4.5 stars, 15-year heat exchanger warranty, and condensing technology that is reliable. Noritz, Japanese brand founded in 1951, is also highly reliable, with 4.5 stars and long lifespan. Rheem and A. O. Smith tankless are also reliable but ranked slightly below Rinnai, Navien, and Noritz for reliability. For most reliable, Rinnai is often considered number one due to Japanese quality control, long history since 1920, and excellent warranty support, with Navien close second for high efficiency and value. So most reliable tankless water heater brands are Rinnai, Navien, and Noritz, with Rinnai often ranked most reliable by plumbers and consumer reports for fewest issues and longest life.