That's more of an addon. We should compare these boards from vanilla. I've just looked at the phpbb3 demo and it's APC. I wouldn't say it's as large as vBulletin's ACP, it's much cleaner than vBulletins ACP I must say, but I wouldn't say it's as large.
You can have a go at a demo at
http://www.vbulletin.com/admindemo.php
You'll see the difference in how much there is to play around with if you do have a go at the full featured demo. I wouldn't say it's as large as IPB's ACP either. I can take screen shots tomorrow if you really want to compare them, I've looked at Phpbb3 ACP, it looks nice, but I wouldn't compare it to vBulletins acp nor IPB's ACP. I'm more on the side of vBulletin though, seeing as I own several licenses with them and I've never actually had a forum hacked using there system.
It really comes down to personal preference. You either like some thing, or you do not and if you don't you're obviously going to be biased towards such forum scripts.
Some say paid licenses cost to much, but then others with licenses say it is to cheap as they can gain more than what they paid to get the software in the first place. Personally, I think the latest version of IPB has far more options than phpbb3. Don't get me wrong, but that's just in my opinion. I have yet to state any facts, but just viewing a phpbb site and IPB site you can see a lot of difference in the amount of features when compared.
And which is personally how I feel, I believe there is a feature list yet to be discovered on IPS and PHPBB.