Tankless DHW and separate Tankless Boiler ( at a later date)

DR650

I am in the process of switching over to nat gas tankless hot water heater from an old electric 50 gallon. . Just had gas run to house. Thinking of going with Rinnai or Rheem Non-condensing 80-82% Efficient instead of condensing . I know the wave is going with condensing but the non's seem less complex . The concentric vent pipe is more expensive but I only have about 15' run ( up 3' over 12' ) . Any thoughts on this way of thinking ?

1962 brick ranch 1800 sq ft. mid Atlantic region that has non funtioning baseboard heat that I may bring back online in the future . Had a Burnham Electric Boiler (55k btu) wall mounted energy pig that's been removed. Circulator pump went bad and local HVAC wanted $ to fix it . I did use the system in the past when it got in the teens for a couple of years. . Currently heating with 6 yr old 15seer heat pump ( all electric ). It's ok but baseboard is pretty comfy .

With all that being said I get a lot of push from HVAC contractors to get a condensing combi- boiler but I hear a lot of negative stuff when they break .