Saw the topic on reddit, and honestly I think it’s worthy of a general thread here.
No hard rules. I’d say keep it to extinct species rather than specifically dinosaurs.
I’ll start with my own favorite:
But I also have a deep and abiding love of all the armored animals out there
Including the Glyptodonts:
And even modern animals like the Pangolin and Armadillo.
Runner up for me is the Paraceratherium.