First of all, readability.
( and this is the main reason of most RegEx I've added )

IMHO the second one is more perceptible as:
```Then I see "user register" page```
Where the text inside **""** is the complete $pageIdentifier,, and have the "page" at the end of the sentence to imply it is a page were talking about.

And since this is to be an assertion, ie. an Then sentence, is not very clear that it really is an assertion, this was the mistake that happen:
https://github.com/ezsystems/DemoBundle/blob/master/Features/start_page.feature#L21

As this last sentence is going for an Given sentence and not a n assertion Then sentence
( https://github.com/Behat/MinkExtension/blob/2.0/src/Behat/MinkExtension/Context/MinkContext.php#L32 )

So using "see" or "should see" at an assertion sentence is probably the best way to go (imo)