In terms of tech, your site should allow both www and no-www and redirect to your preference. Beyond that… Yeah, doesn’t matter. There’s no SEO benefit one way or the other, just in consistency. There’s no technological reason to have it or not, either.
In terms of pure preference, I go no-www as it’s less typing and looks cleaner when typed out.
@paulie_d with or without is all the same to Google (they have publicly said as much). What they say is just make sure you’re as consistent as possible and to use the canonical meta attribute to make sure search engines see it as one page, with or without www.