IBM (of all people) have an article about how to conduct a competitive analysis on a website.
It’s an interesting approach, which provides a blend of statistics and subjective measures. As part of a pitch around opportunities, this could be a good start, and the statistics could provide a dose of pseudo-credibility that just your personal opinion might not be able to deliver.
I noticed though, that an analysis of the users and their needs wasn’t included. Your site visitors and their drivers should be included as well. For instance, a government website is probably a monopoly in its area, so the visitors are probably only going there because they have to, not because they want to. With this in mind, ease of access to information should be a priority, and something to measure.
So this would be a good start, but I’d put some work into understanding the users of both your current site, as well as the competitions, and contrast their different needs (if any).