Alright... apology accepted.
To be honest, Wesker would actually make a pretty good Virgo, but I wouldn't put his vanity on the list of distinctive traits because Virgos are rather known for their low self-esteem / inferiority complex than vanity. However, they're also perfectionists, and that's definitely a trait that Wesker shares.
I completely agree on
Claire, I've always seen her as a Pisces. Now here's my analysis for the other characters. Take them with a grain of salt.
Leon:
Gemini. Basically what you said about Ada, Leon seems to be a different person in every game/movie he appears in. I don't know if Gemini are really known for not being very emotional, but if they are, it would be yet another fitting trait, since Leon displays a rather cool smartass attitude most of the time. He does have some Leo qualities too, but his birthday can't be in the second half of the year for the same reason Chris is most likely a Cancer (his official age statements wouldn't add up with the months in which his games take place). By the way, Gemini are often bisexual and have incestuous tendencies, but I don't think Leon is bisexual.
Ada:
Scorpio. Mysterious woman, no one really knows who she is and what she's up to, she can be caring towards people she likes (Leon), but will stop at nothing to reach her goals. According to statistics, Scorpios are among the most likely murder victims, et voilà, the whole BSAA and probably also some other organisations are after her. They are also known to have a
very strong sex drive, but we can't say anything about Ada in that respect.
Helena:
Aries. Probably the most aggressive and bossy female character we ever had, it was
so predictable that Leon would end up with someone like this, as he always does. She's very passionate, brave and loyal to the people she cares about, like Deborah, who she doesn't want to give up even though she's turned into a monster. On the other hand, she doesn't care much about the rest and puts her own goals before the well-being of any civilians in Tall Oaks (which is, however, understandable given the circumstances), and she can be dangerous when upset, which Deborah's ex-boyfriend had to experience first-hand.
Jake:
Leo. Probably the character with the highest self-esteem and even more of a smartass than Leon. Jake is ambitious and optimistic, but also bossy, mean at times and, most of all, materialistic. Seriously, if he always charged 50 million dollars for his services even before he met Sherry, he must be very rich today, yet he still keeps on working as a mercenary just for the money. His distrustful attitude is the only thing that doesn't fit in, since Leos are rather naive and extroverted in most cases, but it's justified considering his past.
Sherry and Chris:
Cancer. They're both caring and loyal, but also hypersensitive and touchy at times. For example in Sherry's case, when Jake tells her how his father's character might have affected his own, she seems to take offence at it, even though he wasn't even talking about her. Cancers usually aren't leadership personalities, which makes Chris's position in the BSAA seem odd, but they
do wish everything to go according to their will and are very family-oriented, which might be the reason why Chris views his organisation as a big family rather than just a bunch of expendable soldiers. Lucky for Chris and Sherry, they are born fighters, because if they weren't, they would probably depend on social benefits. That's the thing with Cancers, they're agreeable personalities, but also clumsy and not really good at anything.
Jill: I have difficulties analysing this character for how little we really know about her, but if she's the kind of person I think she is, she would probably be a
Taurus. She seems cold and unemotional on the outside, but also has a friendly and caring side she just doesn't let everyone see. She can be distrustful and stubborn, but only to protect herself and the people she cares about. Once she has set herself a goal (like bringing Umbrella down), she's quite determined to reach it, which makes her a very reliable companion. Taurus people are said to fart a lot, but I've never heard Jill fart in the game, so maybe she's the exception to the rule here.
Piers: I like to think of him as a
Sagittarius because of his skills as a marksman, but the amount of fitting and not so fitting traits is 50:50 at the moment, so I'm not sure yet.