US and UK are the best. India is coming up every year, currently the media spend by companies focuses on TV in India. Around 4% of total marketing expenditure is on internet. In UK the ad spend on internet has surpassed that on TV in 2008! - Citrusweb
For English speaking countries I would work on the UK and USA, maybe Australia and Canada but my main focus would be the first two.
I always tend to advertise in the United States and the United Kingdom. These are the best countries to advertise in. In my opinion. I guess it depend on where you are located and what type of prospect you are targetting.
What is your product? How can people pay? Maybe Germany, Austria - bids is not so high, as USA, but people payfull.
Yes the product category should be the most important variable in helping you decide which location. Even if it is not a physical product, the information / content will govern the end reader and thus the location. I think for generally applicable topics US and UK are by far the best. - Citrusweb
I make sure that for all my clients who are targetting overseas users that they have a landing page for each country with country specific copy (colour in Aus/UK vs color in US) as well as buy now buttons in local currency. Paypal users will find this easy. I have found from experience that I am able to achieve a far superior CTR and conversion rate in Australia. Maybe because I am Aussie and think like an Aussie? Only downside is that you won't get as much traffic from Aus compared to UK and US. While conversion rate is usually high is Aus the number of sales in US/UK usually is more than in Aus, which is fine so long as you have ive ROI.
obviously english speaking countries are the best, generally in order of population. then from there hit up the big ones china and india then follow up with the western european players. that formula is pretty traditional but it has obviously been working for everyone until now!