The 'Top 5' is another 'which is the best...' question and therefore a bit hard to answer - the answer varies according to who you are and what you need it for - and also what your budget is. This last applies especially in commercial CMS as some need a budget of $100k up.
You've supplied some criteria, which makes it a little easier. Probably, 'which are the most expensive commercial cms' and 'which are the most popular commercial cms' are questions that are more easily answered than others. 'Practical' or 'stable' are often subjective measurements although in the area you are enquiring about, are presumed to be standard qualities, although budget restrictions make a difference. Also, 'practical' is an entirely subjective user value. I'd define it as ease of use plus capability at low cost, but someone else would put a different measure on it.
'Stable' infers both high traffic and high page number capability, this can only be determined by asking users of those apps who have large, heavily-loaded sites. Stability is also strongly affected by how much the CMS is extended, since a basic site will inevitably be more solid than one with several major add-ons.
You will also find that a PHP codebase is not necessarily the standard here - there is no standard in commercial CMS as many use Java, ASP, or even TCL. So if you restrict the results to PHP-based CMS then you are effectively selecting a group that may be neither the most popular, 'best', or 'top'.
Here are the top 3 most expensive commercial CMS:
Broadvision
Teamsite
Vignette
[though Broadvision has some less-expensive solutuions now]
'Most popular' by installed site numbers is going to be a hard one to answer, as the stats aren't found easily, or validated for that matter. You might find that the cheapest commercial CMS that is advertised widely is therefore the most popular, for example - which would be Ektron.
However, the question of exactly how to evaluate semi-commercial PHP CMS is important here, as the numbers are significant. For example eZ Publish might be seen as an open-source CMS, or as a commercial one, depending on your viewpoint - as a semi-commercial one it can swing either way.
The core is open-source, the plugins are mostly commercial, and any install except DIY is commercial. A commercial install is commonly from $10k thru $45k depending on what you wanted. Although in theory you could have a basic DIY install for zero, most livesites would have cost a substantial amount. I'd probably describe this as the most popular commercial PHP CMS, as for all practical purposes it's paid not OSS, and it probably has the widest userbase of any fully-capable commercial PHP CMS.
In Java open-source CMS you have the same thing, with Alfresco for example. It can be either OSS or commercial, but realistically, there can't be many free installs of this Java CMS, and most cost from $30k to over $200k - so they're all commercial.
Your other requirements are functions / features. Functions are major capabilities that normally have to be a core requirement, features are usually plugins. Some commercial CMS have few plugins so are expensive to add to.
# User contributions
- this is the differentiator between a provider-consumer CMS (run by one person or team) and a community - multi-team CMS (contributed to by many).
# My page / dashboard
- if you mean a user profile / control panel for registered members, most CMS have this; if referring to the admin / backend, again, all CMS have this. In both areas, of course, some are 1000% better than others.
# Mail form
- all CMS have this.
# Events calendar
- it's a plugin.
# Classifieds
- again, a possible plugin, though not all CMS will have it available.
# Wish lists
- this is normally a feature of an ecommerce application, or here, a shopping cart plugin. So first find a CMS that satisfies your requirements in the ecommerce area, then see if that has a Wishlist plugin. If not, and especially if it's PHP (which has a lot more coders than any other type), you can get the plugin coded.
Lastly, everyone wants the perfect CMS or the best CMS. There is no such thing. The best CMS for you will depend entirely on who you are, what your budget is, what you want to use it for, and what your personal scale of values is for the various options.
For me, quality is the overriding factor, assuming all others are met. My way of defining this would be as a measure of all visible quality factors (such as clean code, W3C validation and standards compliance, and good accessibility score), combined with search friendliness (acceptability to search engines - which in practice is a combination of all the preceding factors - ie a good measure of the overall quality score). If the admin is easy to use that's a bonus - but often missing.
Another interesting question you could also ask to determine an answer to the question of which CMS are of high quality is, "Which CMS have existing, provable livesites built to accessibility level AAA?". Only those of the highest quality can achieve this, or at least, at a sane cost without having had to be totally reconstructed. There are some Java CMS out there of appallingly low quality, and high cost seems to make no difference. There are plenty of high-cost trashy ASP CMS as well - so maybe you need to ask, "Which CMS should I avoid?", which is just as valid a question as which ones to shortlist.
So, for a wrap-up: commercial CMS use many codebases apart from PHP. If your features list is by any chance what your project client needs, then I'd go for Drupal or eZ Publish, assuming that a standard web publishing solution is needed, along with ACL and a reasonable number of plugins, plus the possibility of coding them if they don't exist. The end cost would be minimised then, which seems the best idea for an .edu project.
By the time you're done, the result will be commercial even though one starts as OSS and the other is semi-OSS. Drupal is a PHP app that can be remote-installed on any LAMP server, ie standard hosting. eZ Publish has an unusual PHP usage and therefore is best placed on a dedibox or one with all-eZ products. It also uses WebDAV in case that's of interest; and will cost a lot more than Drupal by the end of the project. To compare these with the functionality / features of other CMS, the simplest way is to check out cmsmatrix.org, which has a nice feature list / matrix. But remember that a check in the box just means a feature is basically present, it doesn't tell you how good it is or what the problems with a given CMS are.
The issues that each and every CMS has is a whole different subject
