1. The visitors of your web site (the end consumer)? 2. The advertiser who places Ads through Google on your site? For me, if my site is small, I perfer the second one. But if my site has been large engough, I will choos the first one. How about you?
the second is not actually your customer. becoz they will not pay you unless the no.1 pointer clicks on their ad.
For me the visitors of my web site is the Customer for me because without them we can't get any clicks.
Have a attractive content for your potential user, attract as many user as you can, than the advertiser will visit your site