Hm, jumping on late...
Favorite characters...hm. Well most of mine have already been said.
It was the "Capellan Solution" books that firmly got me hooked to the CapCon. And while there are certainly aspects of the social and political side of the realm I vehemently dislike/disagree with, there are still many things I like.
But anyway, back to my picks:
Sun-Tzu - Monster, murderer, mad man. Just a few of the commonly held views on arguably one of the most successful Chancellors the Confederation has ever had (I rate him up ther with Aliesha, Ursula, Barbara & Ilsa. Funny how all my favorite Chancellors are women. Kind of why I'm hoping Danai CL dethrones Daoshen). A man willing to rain fire on innocents to chase his mad dreams of power. And yet, none of these views are quite the truth. Yes, there is a ruthlessness to him, a willingness to do whatever it takes to make the Confederation stronger. Yet, it is not merely for personally power that he directs such actions. It is from a truely deep concern for the well-being of his realm that acts as he does. He would give his last breath, his soul even if it would make his people stronger. What other leader of his generation could say the say? Victor? A man dedicated to peace? If that were true why did he wait to remove his sister from power when he had the chance to, instead of waiting until she forced the issue. 5 years and millions of lost lives could have been prevented. Sun Tzu would never had let such a calamitous outcome befall his people.
Aris Sung - Well, as I said, CS books really got me into the fold, so he's certainly one of my heroes of the CC. One of love the audacious way he joined House Hiritsu. Second I really enjoyed reading about his growth as a character. Could have been just another MechWarrior fighting for king and country...but, he isn't. One of the best things he did was not on the battlefield (well...okay, it sort of is but bear with me), it was changing the focus of the CC-St. Ives war, at least for House Hiritsu. By the time he was in combat, the war had gotten pretty bloody, pretty much a blood-feud. But Aris realized that it couldn't continue that way, things had to change. St. Ives wasn't an enemy to be conquered, they were cousins, long lost, that had to be shown how far they had strayed. (As an aside I believe this is how Sun-Tzu genuinely feels about all of the sundered Capellan worlds. Not as another conquest to add to a list of accomplishments, but as returning lost and fallen children to their rightful place in the universe. Even if it must be done sternly.)
Talon Zhan - I really enjoyed reading the interaction between him and Sun-Tzu. Most certainly, though rarely credited for it, one of the most gifted strategists of his generation. I don't think he would not have risen so high in any of the other Houses: quite simply most of the other leaders were all military men(or women) and wouldn't have given much thought to asking his advice, let alone letting him wage the conflicts of his day as he saw fit.
Ion Rush - Well...we share the same name, so he'll always be a favorite for that simple fact. As a character, well, he could have become just another DC only in charge of the Warrior Houses, and yet he is more than that. To me he embodies all that is worthy in the Capellan Warrior Houses.
And finally: Cassandra Allard-Liao - Have to agree with Arkansas Warrior about her. Along with Aris Sung, she is certainly my favorite character in the CS duology. I tremendously enjoyed reading her story and Tamas Rubinsky (BT hasn't ever really done romance between characters well, I think this is one of the very few that actually works). And Rubinsky's Light Horse became my favorite Merc faction. The fact that they didn't show up on the rolls of active Mercs is about the only thing I have left to hate about the DA now. (I did ask the writers what happened to them in the intervening years between the Jihad and DA; was told "Don't know, hasn't been written".)
How about least favorite character? Mine is Kai. He was cool up until he turned traitor and joined the Republic (Of all the factions he could have joined...). I guess in the end he was more Davion than Liao. I'll just say his ending was...fitting.