Argonians for me. It's partially because they were my first pick in my first Elder Scrolls game. I usually tend to skip the standard races, so I just glanced over the elves and humans. Argonians were something new, so I tried it.
As for the other reasons, here we go:
We still don't have much knowledge about their lore, but what we know makes me rank it along with Altmer lore for the most interesting.
I really like their resistance to disease and poison, as well as water breathing ability
Their Skyrim designs are beautiful (Oblivion not so much and in Morrowind nobody looked good)
The backstory of Black Marsh being a hostile place to every other race, but Argonian makes me happy. Why? I wouldn't call it elitism, but an affinity for mysterious, unknown, hidden, reclusive or however you want to call it
Lastly, I'd like to note that I could never really identify their culture with "me", as their lore is alien, but they've still become a favorite of mine
Anyway, my thoughts about their lore? I think it got more awesome as we got new details. More specifically, I really love anything related to the Hist. It's not much that we have, but it raises imagination. Hmm... if we only got Kirkbride to write Elder Scrolls: Black Marsh.... ahem, sorry for this digression. I felt they were quite under represented in lore until the books came out. They never got any kind of spotlight, I can only guess why Bethesda decided to make them a playable race and keep them throughout the games. They've just been there, on the sideways, for the most part. That may be the reason why ES boks focused on them a lot more. With the successful banishing of daedra during oblivion crisis and devastation of Morrowind, I think the author maybe overpowered them a bit in his try to make them relevant. However, I do not object to it, my hope is that they get more integrated into the "Tamriel wide plot" more, in the future games.