Do you want a counter to display on your site so your visitors can see how many hits too?
If not, Google Analytics is awesome. It's a really indepth traffic analysis tool that can give you masses of data on your traffic.
And I might also add that counters that
do get displayed on the site don't really add much to any website - they were all the rage in mid-1990s, but a lot of web design gurus started speaking against them. And it's pretty common sense, really - big hit counts impress no one, and small numbers don't really inspire pity or confidence either
You probably want to also choose a counter that's hosted on a reasonably fast host, because people don't want to wait the pages to load too long, especially if the remaining bits are just ads or add-ons that don't help the user (like counters). Another point in favour of Google, who generally have pretty fast and reliable web services.