Best heating to install for a total rehab in Northeast

[Deb Merrill]

Working on a rehab to the studs if a 2 family in a high end tourist destination. The current heating system is natural gas with old cast iron hydronic radiators.  I can easily add ducts since the ceilings and walls have been removed. Looking for feedback on replacing the current single unit furnace with 2 systems that will appeal to higher end renters.