I use MyBB its very nice and its really secure, they have really great support and ACTIVE staff/members on their forums...Ive been using it for a long time and never once had problems with it, however with phpBB I've had MANY security problems with. My Crew and I decided after hearing rumors how long it would take to see forums get hacked, or someone try to...In our test we ran the following forums
MyBB
phpBB
IPB 1.3
YaBB
SMF
IkonForums
E blah
and many more..We found that
MyBB: Not Hacked (easy to install mods)
phpBB: Was hacked 3-5hours afterwards of having it
IPB 1.3: Surprise or not, it wasn't even touched
YaBB: Was attempted, but didnt happen however we did have problems with Spam Bots:
SMF: Wasn't touch, (easy to install mods)
IkonForums: Had problems getting to install
E Blah: Had problems getting to install
Also some background on my Crew and I, we are professional testers, pretty much we run a community and people tell us some problems they are having with forums software, free hosting companies and all that...What we do is try to help that subject (ex. forums, free hosting companies etc.) and if we find any problems we report it to those people...Our goals is trying to make the internet a little bit safer for all of us, so we post and advertise tons of "Companies" and see what happens..