Question about generator size to power a home?

I have a 5000/4000 continuous run taking care of my furnace,basement lights,fridge,lights & tv upstairs and used it many times and am happy. when I replace it I'll go with 5000 continuous because I like having more than I actually need and electric start which I suggest you get. I highly suggest you get a transfer switch for your set up for safety reasons and convenience , don't let anyone talk you out of it ,It is the safest and smartest way. talk to a electrician If he says you don't need one get another electrician.