Hi, I was wondering how you decide whether to release your books out into the wild or gift them to fulfill a wish?
I do a lot more wild-releasing than wish-filling, but I do like to participate in the occasional RABCK or trade or bookbox or other swap-type thing. If a particular book is especially unusual, quirky, or interesting, I might check to see if anyone's wishing for it; if so, and if they're in locations that I can afford to mail to, I may dig deeper to see if they've been active on the site at all, if we've exchanged books before, if they already have a copy of that title... If everything pans out I'll send a PM with an offer to send the book, and (if it's someone I don't know or haven't contacted recently) with a deadline, as in "If you're interested, reply within the week". (That way I don't have to sit on the book indefinitely; if there's no reply by the specified time I can offer it elsewhere or just wild-release it.)
I do recommend doing at least some wild releases, even if you think you'd prefer to swap or give away books by mail. Mixing it up can keep things interesting - and may win you some new local BookCrossers!
I much prefer wild releasing and the vast majority of my releases are left in the wild. Some people never do them, even though that was the original intent of the site. If a stranger finds a book in the wild, it may inspire them to join up and join in. Giving books to people who are already BookCrossers isn't likely to bring in new members. And there's nothing like your first wild catch to make you do the Happy Dance!
But when you get down to it, it's a hobby so it should be for fun and enjoyment, so it's entirely up to you. Do whichever you enjoy more. Or do both.