For the Phantoms, there's a nice comparison page on DJI's site that goes over the features/benefits of each model. Which one you choose would depend entirely on your need and individual preference.
http://www.dji.com/products/compare-phantom
There are a number of other options, too, certainly... and more are appearing in the market every day. This is a Phantom-specific board, so I'd guess that the majority of folks here would tell you to go with DJI. And DJI is probably the most mature of the consumer drone manufacturers. They're nearly on their 3rd and 4th generation products, while most other manufacturers are just coming to market with their 1sts. I happen to think the DJI's work incredibly well. Some will disagree. So, again, it really comes down to personal preference, and what kind of experience you're looking to get out of your purchase.
Of those other manufacturers that are putting out units of the same size and calibre as DJI, Walkera is another popular choice, as is Turbo Ace. But, interestingly, you'll find that most of these other products use DJI components, such as the NAZA-M controller, often the same controller that is inside the Phantom. So, other than some features unique to each platform, there often is little differentiation.
Though you're going to start seeing different types of drones that may or may not appeal to you, again, depending on what you actually want to do or what you want out of your equipment. The Air Dog (
http://www.airdog.com/), for example, is a photography drone that will automatically follow you. Pretty cool technology. But if you have no interest in selfie-videos of you on a surfboard, there might be better choices for you.
So... I guess the question is... what type of flying do you want to do, and what do you want to get out of your drone and your experience?