I'm starting a website/online community that will have a lot of tutorials and articles on it from many different contributors. So the software I use needs to have some sort of CMS and forum. I really like the look of xenForo, but from what I've read there is no CMS yet.
You are not really requesting a CMS ... you are requesting an Articles Addon.
vBulletin's horrifically terrible CMS is really just a mediocre Articles Addon with poor implementation. Add a dose of bugs and sluggish performance ... and that's about it.
A real CMS is much more than just an Articles Addon.
(1) One idea would be to run a Wordpress site .... maybe with a good blog and good articles .... you would get the SEO goodness from that ..... and then just run Xenforo as the Forum Tab on your Wordpress site.
I'm sure Wordpress has plenty of good Articles Plugins.
(2) The [LN] Blog is multiuser ... and might work for your needs with some tweaks ?
(3) I don't think there is a good articles addon ... yet.
But one is probably coming relatively soon.
Most of the VB user feedback is hidden in a forum available to licensed users only. You may want to look at the bug tracker or check third party sites like TheAdminZone.com for some of the issues people were experiencing with the CMS.