I use a Daylight computer, and dark themes always look terrible on it. I'm obviously in the wildly small minority for this case, but I appreciate at least having the option for a light theme for things.
So I agree, default to whatever you want but definitely keep an option for a light theme available for those few of us that prefer it.
FWIW I don't prefer white themes either, I like something like solarized light or gruvbox light