Yeah, most of these are fun to think about, but the slow killer robot thing always bugs me. Two words: Phalanx System.
Someone asked, "Which show gets it the most right?" I would say it's a combination of Caprica's Zoe bot, The Expanse's space physics, and Firefly's frontier melding of languages and superpowers.
Oh, and if you can slog through the patriotic crap of John Ringo, check out "Through the Looking Glass" series of books for what 'alien' encounters might be like.