I wondered if the Adense stats 'impressions' is a better gauge to the actual amount of unique visitors ?? I use Webalizer for reporting, but the stats seem way over optomistic, whereas Adsense stats seems more reasonable. What's your experience ??
Impressions is in no way better then real analyzing of web stats logs. Ads are often blocked before even loaded (e.g. by ad block plus) Therefor I suggest you stick to webalizer, use awstats or gooogle analytics