OK, so there was a pretty strong sentiment that the Borg shouldn't be a playable faction in-game. So my question to you is: what races would be distinct enough for you to be interested in playing them?

It seems to me that Klingons are different enough from Feds because they have little scientific or diplomatic interest, it's all about battles, and just a generally different outlook on the galaxy. I could even see that Romulans, if done well, would be different from Klingons, maybe using stealth, subterfuge and general sneakiness to try to meet their goals.

But are Cardassians different enough from Klingons and Romulans to make them a viable candidate for playable faction? What would make them (or another race) interesting enough for someone who has already got a top-level Fed and Klingon to come back to the game and play?

One difference that might work is if a new race used completely different technology, unavailable to the established races. Not necessarily better, but different. Another would be if their goals were different from the usual (but then how do you incorporate that into the game?).

Cardassians, Kazon, Hirogen, Suliban, Imperials, they all seem like shades of Klingon gray to me. So what would make them appeal to you as a gamer?

Though the Cardassians are relatively militaristic, they also tend to be a bit xenophobic. I could see some of their play getting into some realm of introspective empire improvement as well as some diplomatic and some Romulan-esque subterfuge. Not to mention that now there is the whole Dominion component. Multiple factions of Cardassians, internal struggle both with and against the Dominion, plus the cool factor of being able to play a Vorta or Jem'Hadar.

Even though a lot of the same themes (military, diplomacy, etc.) will be repeated in all the playable factions, I think the interest comes in exploring that particular faction. How do the Cardassians interact with the Romulans? How would the narration change the game experience coming from that species? What would the storyline of the missions be even though the tasks are similar?

I think they would be the next logical step, though. They were the next most highlighted race in the Star Trek universe, especially with this period in history. I think the developers could make them interesting. I've been impressed with some of the additions that they've added lately. With the input of the players, I'm sure they'd get some great ideas.

Romulans should be next, to complete the TOS trinity, as it were. Traditionally have somewhat different tech, and their current sociopolitical situation would make for great story.

Next should be Dominion. If we're talking difference--technology, species, motives, cultures--you have it all right there.

I could see the Cardassians done well in a way that reflects their OCD-like attention to detail...

Perhaps a future update that allows us to use Starbases and/or ground bases for trade, either abstracted with NPCs or directly with other players... Cardassians could be especially suited ot that, to make them different from either the Fed (exploration) or the Klingons (battle!)