There is no reason one cannot do both, is there?
If you could only choose one, why choose the smaller one of the two?
AdWords is more than 10 times larger than Bing Ads, and offers far greater reach, for those reasons alone you are getting more bang for your buck, especially if you plan to scale your campaigns. And if your campaigns are profitable, why wouldn’t you want to scale up?
Let’s say, for argument’s sake, that you can buy clicks cheaper on Bing Ads due to Bing having far fewer advertisers to compete with, and let’s say for the moment that you are able to make twice the profit per click on Bing as you can with AdWords. You will still make more money on AdWords, here is why: volume.
Let’s say that you make $1.00 per click on Bing Ads and only $0.50 per click on AdWords. Because the volume and reach are far greater on AdWords you are like to make even more money on your AdWords campaign.
Let’s do the math:
Avg. Profit per click on Bing Ads = $1
Number of profitable clicks available on the Bing Ads network = 1,000
1000 X $1.00 = $1000 total profit on Bing Ads.
Avg Profit per click on AdWords = $0.50
Number of profitable clicks available on AdWords = 10,000
10000 X $0.50 = $5000 total profit on AdWords.
Now let me ask you which is better: $1000 total profit, or $5000 total profit? (this is not a trick question, the obvious best answer is the correct answer).
People who myopically focus on “cost per click”, rather than total profit, are frequently making poor decisions as a result.