I use 3 trackers on my sites, takes some bandwidth, but is needed... never use only one statcounter... That's my advice for today
I typically don't have a problem with G's analytics. The numbers are usually lower, but it doesn't count bots, or crap hits. If G counted it, it was most likely a real person. Logs track everything, including hitting the refresh button 50 times in a row. Who needs those kind of numbers? I say pick whichever one you like, I like G's, and stick with it. You should be looking for trends, and general numbers, not I had 876 visitors today.
Yes, From Google analytics it is difficult to find exact numbers unique visitors per day. If a person visited twice then it will count him twice accordingly.