I find it ironic that other on these boards have written that the Bajorans' antagonists, the Cardassians, were the most fleshed out Trek species. Of course, we don't see a variety of modes de vie--professions, belief system, etc. Indeed, we see little civilian life life, and almost no life that is not touched by the state's institutions of violence and surveillance. Among the Bajoran scientists trying to build a communications system into the Gamma Quadrant is a member of the Obsidian Order. The only civilian who we encounter in a sustain manner, Mila, is clearly affected by the military's reach into public life. And I don't think it's clear that the civilian government of the fourth season really overturned the Guls' hold on the state. Of course, Cardassia is presented as a militarized society, not something that is unrealistic. What we do see is a deep exploration of Cardassian psychology and mentality. Although Garak, Dukat, Dumar, Evek, Mila, ..., have distinct personalities, it feels as if they share a Weltanschauung that is unique to Cardassians: about truth, the future, order, discipline, love. They are always ready vivdly to express how their outlook is different from humans'. I particularly find it interesting that in the context of Cardassian society, Dukat may be loving and merciful. Civil Defense goes a long way to showing how different Cardassian values can be, whether they involve justice or love (I love when Garak calls out Dukat for flirting with Kira when it looks like he's just being an asshole).
I wouldn't suggest that Cardassians are a better fit for most fleshed out species. However, I find it interesting that two of the most obvious answers were not just fleshed out by the same series, but they were enemies and rivals. Staying in place, the show had to explore both sides of a complex and antagonistic relationship. Throughout the series, there are ways that a relationship with Bajor affects Cardassia, becoming an indirect influence toward reform, until the very people who fought against the occupation informed the values of Cardassia's resistance (pro-democracy?) movement. ETA: I should go further to say that DS9 explores the relationships between species more than other series, the Bajoran-Cardassian being the richest.
(Klingons could also be argued to be most fleshed out, though much of that happened on DS9, when they were fighting against the Cardassians over the same piece of real estate.)
I wouldn't suggest that Cardassians are a better fit for most fleshed out species. However, I find it interesting that two of the most obvious answers were not just fleshed out by the same series, but they were enemies and rivals. Staying in place, the show had to explore both sides of a complex and antagonistic relationship. Throughout the series, there are ways that a relationship with Bajor affects Cardassia, becoming an indirect influence toward reform, until the very people who fought against the occupation informed the values of Cardassia's resistance (pro-democracy?) movement. ETA: I should go further to say that DS9 explores the relationships between species more than other series, the Bajoran-Cardassian being the richest.
(Klingons could also be argued to be most fleshed out, though much of that happened on DS9, when they were fighting against the Cardassians over the same piece of real estate.)