What's selling better: iPhone 6 or iPhone 6 Plus?

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Apple's first phablet, the iPhone 6 Plus, has been well received by consumers, but its smaller-screened cousin is far outperforming in terms of sales, according to new research.

AppLovin, a mobile advertising firm, estimates that the 4.7-inch iPhone 6 accounts for 80 percent of new iPhones in use globally, with the 5.5-inch screen iPhone 6 plus taking the remaining share.

The firm, which processes 25 billion ad requests daily, looked at the high volume of data to ascertain its estimate.

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"Since interaction and usage differences between the 6 and 6 Plus on our network are negligible, it's fair to estimate that roughly one in five new iPhones sold is an iPhone 6 Plus," AppLovin said in a blog post on its website.

The highly-anticipated iPhones were unveiled on September 9, drawing enthusiasm from consumers worldwide.

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In their debut weekend, Apple sold 10 million of the devices, up from nine million sold when the previous generation of iPhones debuted last year.

Bigger is better, in Asia

Western nations have demonstrated a clear preference for mid-sized phones, but the same cannot be said for Asia.

In countries such as China, Japan, Vietnam and the Philippines, the iPhone 6 Plus accounts for 35 percent of new iPhones in use.

"No one expected iPhone 6 Plus to match or surpass the heights of iPhone 6, but usage was more robust than expected -- especially in areas where phablets are already popular," AppLovin said.

Phablets, smartphones with screen sizes from 5.5 to less than 7 inches, have been rapidly gaining popularity given their dual functionality as a tablet and phone.

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So much so that phablet shipments are even expected to top 318 million units next year, surpassing the 233 million estimate for tablets, according to research firm International Data Corporation (IDC)

"While consumers in places like the United States and Western Europe are likely to own a combination of PCs, tablets, and smartphones, in many places the smartphone — regardless of size — will be the one connected device of choice," IDC wrote in a recent report.