Even though all the growth in Apple’s Mac business is in MacBooks that accounted for nearly three-quarters of all the computers Apple sold during the September quarter, the iMac has been by far their most popular desktop. In fact, it’s the world’s leading all-in-one system in terms of popularity, recognition, visibility and – most importantly – sales.

According to a DigiTimes Research analysis, some 13.5 million all-in-one PCs will ship this year and iMac will lead the charge with an estimated 3.7 million shipments, beating both Hewlett-Packard and Lenovo which are expected to move 2.4 million and 2.9 million all-in-ones, respectively.

In 2012 Apple, all-in-one shipments will rise to 15.8 million units, accounting for 10.5 percent of the overall desktop market (9.3 percent in 2011). Apple’s baby is projected to surrender the top spot to Lenovo which should ship four million all-in-ones versus 3.8 million iMacs. If true, the iMac’s share of the all-in-one market will drop from 27 percent in 2011 to 24 percent in 2012.

Lenovo should benefit from reduced prices of its systems and the brand’s popularity in China, which is increasingly becoming one of the key markets for all-in-one PCs. According to the report:

As for the Europe and U.S. markets:

There is no doubt Apple will face tougher competition in 2012. However, the company is expected to refresh the iMac family in 2012 with 22-nanometer Ivy Bridge platform, updated graphics and other perks. Apple does not divulge per-model computer sales and only provides a breakdown of the desktop versus notebook sales so approach the above research with caution.

Another comment by DigiTimes Research:

Apple sold 4.89 million Macs in its fourth fiscal 2011 quarter and the Mac business contributed with $6.27 billion in the $28.27 billion quarter. Even though more than 73 percent of Apple’s revenue came from Mac portables (mostly flash-based MacBook Airs), the remaining $1.69 billion came from hard drive-based desktop machines such as Mac Pro (some) and the popular iMac all-in-one family (the vast majority).

  • Analyst: First Apple HDTV will be integrated into next-gen iMacs (unlikely) (9to5mac.com)
  • ‘Late 2011 iMacs’? (9to5mac.com)
  • Global hard drive shortage affects BTO 2TB iMac: Shipping times slip to 5-7 weeks (9to5mac.com)
  • Refurb Apple iMac Roundup: Core i3 22″ for $929 + free shipping, more (9to5toys.com)
  • Apple iMac Core i5 Quad 2.7GHz 27″ Desktop w/ 12GB RAM for $1,798 + $29 s&h (9to5toys.com)