okay, I'm going to sound OCD a bit, but I have 3 counters on my blog.
Sitemeter, statcounter and google analytics. I like sitemeter, because it's simple and I can see more in real time who visited when. Statcounter shows me more details about exactly what posts a visitor looked at-something I can't see with sitemeter, but I find the tracking order confusing-the days are mixed together somehow. I only recently added google analytics so I could see unique visitors/trending/bounce rate.