Apple's (AAPL 0.56%) stock hasn't gone much of anywhere for nearly three years even though the company is constantly pumping out cash.

AAPL Chart

AAPL data by YCharts.

Maybe it's the fact that Apple's recent products haven't wowed the market, growth has slowed, and competitors are catching the tech juggernaut on all fronts. Despite these challenges, there are a few reasons Apple is still a great buy today, especially for investors looking for value.

Despite losing market share, Apple's tablets are still the most popular in the world. Image courtesy of Apple.

iPad still rules tablets
The iPad no longer dominates market share now that Google's (GOOG -2.05%) (GOOGL -2.00%) Android operating system is spreading, but it's still the best, most profitable tablet out there. According to Gartner, the iPad's market share in tablets worldwide fell from 52.8% in 2012 to 36% in 2013, but unit volume was still up 14.5% to 70 million. And consumers are using their iPads far more than cheaper Android-based tablets.  

Monetate found that the iPad accounted for 87.5% of tablet e-commerce traffic in the fourth quarter of 2013, down only slightly from 91.1% a year earlier. A similar report from IBM showed that iOS users spent $93.94 per online purchase order in the 2013 holiday season, nearly double the $48.10 from Android users; 23% of all online sales came from iOS devices, compared to just 4.6% from Android. Ironically, Google is the standard search engine for iPads, so when all revenue sources are considered Google probably makes more from iPads than Android devices thanks to that revenue stream. 

Safari also accounts for 54% of mobile browsing, according to NetMarketShare. Apple users are using their devices more than Android users, and an ecosystem that will keep users buying new devices and apps is great for Apple's long-term prospects.

The interconnection between all of Apple's devices keep users hooked. Image courtesy of Apple.

Apple's ecosystem is second to none
Once people do buy Apple devices the ecosystem of apps and services is hard to leave. The iCloud, App Store, iTunes, and other services make it easy to transfer data and purchases across the ecosystem, and to upgrade to the latest device. Leaving the ecosystem would force that to all be rebuilt elsewhere.

It's not just Apple's services that keep people hooked. Developers prefer the iOS system, which has the higher-paying customers. These developers create the popular apps that draw more users to Apple's platforms. 

As Apple adds more services like free office software and expanded cloud support, it becomes even more difficult to leave an ecosystem in which you've spent hundreds or thousands of dollars on apps, movies, and more. So people will stay, which is a great competitive advantage for Apple, especially as it expands into new businesses.

TV is on its way
I'll be the first to admit to being disappointed by the slow launch of a more advanced Apple TV. I believe the television market could be as big for Apple as either the iPhone or iPad, and Steve Jobs said years ago that Apple had already cracked the code for this sector.

When Apple does finally release a new Apple TV or iTV, it will be a great growth opportunity and add to that ecosystem I pointed to above. A whole new world of apps will open up, connectivity with its own devices will improve, and Apple could be the center of home entertainment. 

What's great about TV for Apple is that it's almost pure upside. The Apple TV just passed the $1 billion mark in revenue, which CEO Tim Cook says makes it more than a hobby, but there's still a lot of room to grow. 

Apple's stock is a buy today
Apple may not dominate tablets or smartphones the way it used to, but it still dominates at making money selling tablets and smartphones. In the past year alone, Apple has made $37 billion in net income, generated $52.9 billion in operating cash flow, and had $158.8 billion in cash as of the end of the year.

I see the competitive moat as too strong and the value too good to avoid Apple's stock today. It may not be the highflier it once was, but it's a great value and has tremendous upside if Apple can get its move into TV right.