When using DC machinery in RV has lot of advantages, replacing the equipment you already have, when you need inverter anyway might not make economical sense.
I do have one of those $19 300W inverters for cars and the cheap fan can be really squeaky.
Than the 1600W Xantrek makes less noise, but for long stay the fan takes lot of power.
There is no "one size fits all" for most of the users and I would consider 2 inverters for motorhome.
If CPAP takes less than 120W, you can buy fanless inverter that will make no noise at all. Just observe cooling space.
Than for microwave get one of those 1000W and don't worry about noise.
Inverter/charger would be top of the line, so would be replacing motorhome with Prevost conversion that will have all the electrical already set.
Your choice