I think some "big" companies or retailers might use a solution from a company like [lithium.com...] But even still, vBulletin is really advanced, and big companies use that too. I can't see big companies developing their own in house forum software that would be able to beat the features of these products.
I would recommend vBulletin any day as an inexpensive industrial strength forum platform. There are a lot of companies and hobby sites using it, so that means good support as well.
vBulletin gets my vote I use it on my own forum
I'll be leaving vBulletin (due to the recent licencing furore) as soon as I've recoded my site integration to use phpBB (and will never use another commercial bulletin board again - well done Internet Brands on putting me off on my first foray outside open source).
Most features is not necessarily a good thing. I won't use half of what vBulletin or phpBB has to offer (not interested in anything other than admin functions and private messaging) and will be switching again if I can identify something with less need to lock down that can run faster.
vBulletin is highly scalable, and although my biggest forum is busy, has a solid revenue model, and could afford any commercial app, I am not contemplating a change. vBulletin is continuing to invest in the product, and the plugin system has made modifying it and periodically upgrading it a lot more straightforward.
That's not to say that other solutions couldn't do the job. Still, vB would be my recommendation. It's the most popular choice among "big boards."
Of the different forum implementations I've used, vBulletin is my favorite as a user and I find it really good as an administrator.
In my research so far I've found that people either love vBulletin, or hate it. Some of the things i've been sent by current vBulletin owners are not exactly flattering, and even make me feel better about my current IPB installation.
What is the licensing kerfuffle surrounding vBulletin? Did a bunch of old licenses become invalidated or something?
I'll look into the Lithium suggestion. Any others are appreciated.
Right now, I'm considering rolling my own solution. Like rogerd, I don't use half of the features my current forum software offers, and worse -- my current forum software lacks many features that my users have been asking for for years.
I'm no programmer, but if I can manage to cobble together a system that does the basics and does them well I'd be better served than something that's gotten far too bloated over the last decade.
Still, I'm open to more suggestions.
Those who choose vbulletin, phpbb, and similar 'big' software after a short while will realize they only need 10-50% of all the features. But still, they have to run the whole thing and wonder why page load times are getting slower and slower when there are more posts and/or users.
From the user experience perspective, I vote for vBulletin (vs. phpBB).
The licensing issue was due to the latest release bundling more features and raising the cost of ownership. We are talking tiny money for a real business, but hobby-type site owners were enraged.
vBulletin CAN be resource intensive. While there are steps you can take to speed it up as your activity level increases, be prepared to throw hardware at it. The one type of community that I wouldn't recommend vBulletin for is a very busy site with little or no revenue. As long as your site revenue scales with your level of user activity, you should be able to support vB's hardware demands without a problem.
Software money's not a problem with the forum I'm operating. Though once you start talking about hardware upgrades to support the forum, I start to get nervous.
I'm caught up in another project right now, so it looks like I'm going to slag along with Invision for at least the next couple of quarters until I can explore the potential of writing my own software.