"There's one particular firm I really want to work for based on their clients, but I'm not sure my personality is a great fit for them. Would it make sense to work there even though I may not fit in?" The best way to figure out if you're going to be a good fit for a firm is really to interview with them and get a sense of that. In terms of the personality types at a firm, a lot of times, people, they're like chameleons, and will adopt the personality of the group they are spending time with over an extended period of time. So if you're spending a lot of time with a certain type of firm and the people there, you tend to adopt their personality over time. That's just something to think about. And you may not be a good fit out of the bat, but you may actually be a good fit in the long run the longer you are there.
If you do want to work with their type of clients, there's probably going to be other firms that have similar clients as well, that may be a better fit for you. Different law firms do have different personalities, and it may make sense for you to try to work in another firm with similar types of clients. If you really do feel that personality wouldn't match, and you don't know also about the personality of the firm, because it really depends on the people you're working with and the individuals in the firm and what their personalities are like. And it may not necessarily be the overall firm personality.