Navien NCB-H Combi or Lochinvar Noble Fire Tube Combi

Neither contractor is very competent if those are the sizes they're giving you, but the Lochinvar Noble 110k would be an excellent choice if you really want a combi boiler. I've got about 150 in service and have had excellent luck with them.

Your original system was a tank of hot water, so the unit could be sized more accurately for the heating system. Personally I would either go with a lower BTU boiler with a small indirect water heater, or a smaller size boiler with a regular water heater. Of the two brands listed I would prefer the lochinvar, they make heat only boilers that range down to a more appropriate size for you heating system, and they also have indirect water heaters to pair with the boiler, they also make standalone gas or electric water heaters (they are an AO smith brand) If you like the idea of the tankless combi then go for it, I wouldn't try to talk someone out of a tankless or combi they just aren't for me personally.

This min heat load on there is your total heat loss at the given design day temp, any combi will be much larger than that and you will need to size to the domestic load. To size the domestic load you will need to know your required flowrates first. So figure as many fixtures that have hot water as you might reasonably have on at the same time and add together their flowrates for your required flowrate. From there you need a reasonably close number for your cold water temperature, what temp is the water coming from your well or city water supply, and what temp water do you need produced at the fixture, that will give you your required temp rise. Most tankless and combi manufacturers will list data to show the temperature rise at a given flowrate, match up your requirements with the closest model for best results, or jump up to the next size for more headroom on flowrates.

I'm not sure what your designer used for design day (your location I think should be 35f), but the load on the report comes out to about 21 btu/sqft which is about what it takes to heat a new house in MI at -10f so I imagine there was already some fudge factor added into your heating load

A 77* rise is highly unlikely in CA unless you like your showers scalding. Average cold water temp is 55-65* so with a 110* shower coming up from 55*, your actual rise is only 55* which puts the 110k at ~3.7 GPM output. I really don't care for a combi in general but as long as you're mindful of the limitations and don't run two showers plus laundry or dishwasher or whatever all at the same time, the 110k should be well suited to the demand.