Apple's iPad continues to maintain a wide lead among consumers because of its appealing design and easy functionality, market researchers IHS iSuppli determined. The result: Apple will dominate the tablet market over rival tablets from Hewlett-Packard, Dell and Research in Motion.

Besides winning overwhelming consumer preference, iSuppli also found that the Cupertino, California-based Apple's traditional dominance of all aspects of the iPad, from design to the operating system and close ties to its contract manufacturers, leads to extra profit.

"Since Apple controls both the operating system and hardware design of the iPad, it is able to attain design efficiencies that other tablet manufacturers cannot," said Wayne Lam, senior analyst, competitive analysis, at IHS. "These efficiencies become obvious in areas like the memory and the battery, where Apple maintains advantages in cost, space savings and performance compared with every competitor in the business."

For Apple, the tight control keeps its manufacturing costs down while allowing it to charge a premium for a hot product. Apple previously reported selling 9.25 million iPads in the quarter ended June 30; both Dell and H-P plan to report their results August 18.

Apple's gross margin on revenue rose to 41.2% from 39% in the 2010 quarter, reflecting continued demand for its entire product line.

Still, tablet sales are far from a monopoly, iSuppli found. Nor does Apple rub out competitors on satisfaction. Apple iPad users ranked their products at 8.8 on a 10 point scale, while customers of China's Zenthink Technologies ranked their tablets at 8.75 and Samsung's at 8.5.

Apple shares have gained more than 50% in the past year. They traded Tuesday around $400.