I suppose it all depends on how many recipients you will have.
I'm not aware of all of them, but there are probs and cons for both.
Sending an email to each individual recipient will allow you to personalise the subject/body, use tracking URLs etc. That said, it will take longer for PHP to send all the emails, depending on how many recipients you have. For example, if you have 250k recipients, you may be waiting a while. In addition to this, it may also put a strain on your server.
bcc will take a lot less time as the process will only happen once, but it won't allow personalisation, tracking URLs and you may run into a bcc limit.
Your best bet will be to utilise a 3rd party SMTP email distributor which will take the heavy load off your hands. Mandrill is one of them but I don't believe they have a free package anymore so you may want to look around for others.