Here's an overview of the number of counts ;-)

To sum it up, Symfony (i.e. you :-) is the only one using "count" at all. And since WebDriver's seeNumberOfElements is probably very popular, I would suggest: Let's go for "NumberOf"!
How: Create an alias for those 5 "count" functions in Symfony, mark them as @deprecated, but leave them in the code for some years (hurts nobody). I could create a PR for that.
What do you think?

I understand. Many of those occurrences in module-symfony correspond to assertions inherited from symfony.

As well as we have assertions inherited from PHPUnit like assertCount and assertNotCount.

A couple of examples would be assertEmailAttachmentCount and assertHttpClientRequestCount.

Renaming these assertions would not be right.

I did not find any occurrences of NumberOf within the module.

With this new information, I'm fine with the Symfony module being an exception.

PHPUnit: If https://docs.phpunit.de/en/11.5/assertions.html is the right page to look at, then it has no numberOf, but some Count.
And I agree that external consistency with PHPUnit is more important than internal consistency with Yii2 module ;-)

The 1 numberOf in Symfony module is seeNumberOfElements - certainly inherited from somewhere.

I just noticed: "see" sounds better with "number of", while "assert" sounds better with "count", take e.g. "see element count".

i would also prefer to switch to `NumberOf`` and deprecate the other functions