Which DJI drone should you get? The choices might seem really confusing so let me help you make your decision. Two of these drones are amazing but they each have their own strengths and weaknesses and you need to match those with what you are trying to do. One of them doesn't make sense. In my opinion, the choice is either the Mavic Pro or the Phantom 4 Pro depending on what you want to use it for.
For the aerial photographer looking to make money shooting small jobs
The Phantom 4 Pro is the best choice here even though it is the most expensive for two simple reasons. The biggest reason to buy this drone over the other two is the camera. The camera on the Phantom 4 pro has a 1" sensor and takes 20mp stills. The Phantom 4 pro also looks more professional than the Mavic Pro and as silly as that might sounds this is important. It has other features you might get distracted by but if you are wanting to make money with your drone doing real estate photography then the Phantom 4 pro is the one to get. It is the most expensive at around $1500 but you only need one or two jobs to cover the cost difference between the Phantom 4 and the Phantom 4 pro. If you want to make side cash with your drone, this is the one to get. The flight times are so good on this one that you can get away with only having one battery, but having a backup is a good idea.
For the traveling aerial photographer
There is a saying in photography circles that the best camera is the one you are going to actually use and the compact, easy to carry mechanics of the Mavic pro make this the drone of choice if you are planning on traveling. You do not have to take the propellers off and the thing just folds up into a tiny little drone carrying bag. Bringing this along is an afterthought and that means you will have it available when those amazing shots present themselves. I can't tell you how many times I have been driving around Maui and I see something so beautiful that would look incredible from the air but carrying my Inspire around with me all the time is completely out of the question. The camera is nowhere near as good as the Phantom 4 Pro or even the Phantom 4 but if you don't have your drone with you, you aren't going to get the shot.
For the aerial photography hobbyist who is not a camera snob
Let us say you do not plan on trying to make money using your drone, you just want to take awesome aerial pictures of stuff. Which drone should you get then? The choice has got to be the Mavic Pro. The ability to carry this thing anywhere is a game changer and it is worth giving up the better camera and feature set of the Phantom line. I have had drones of all sizes and shapes and the bottom line is you will fly more with a more convenient setup. Buy the Mavic Pro.
For the aerial photography hobbyist who is a camera snob
I totally understand where you are coming from. Flying the best possible camera is important to you and worth the extra hassle. You have probably already guessed which one you should buy - The Phantom 4 Pro. If you are in this category, you know you have to at least consider doubling the cost and hassle and try and fly the X5 with the Inspire but I really can't recommend that unless you have deep pockets and the need to fly the best. The Phantom 4 pro is a fine rig and will take amazing pictures and it is the one I would recommend for the photography hobbyist looking to get started. It also has a host of other features like obstacle avoidance that might come in handy if your drone flying skills are not well developed.
Phantom 4 vs Phantom 4 Pro
I think you should either be considering the Mavic Pro for its portability or the Phantom 4 Pro for its amazing camera. The Phantom 4 comes somewhere in the middle and I don't really understand why anyone would choose it over the other two options. Yes, you save some money over the Phantom 4 pro but you still have the same hassles of carrying around a larger drone. It will take better pictures than the Mavic Pro but you will not be able to have it with you all the time.
Conclusion - Portability or Image Quality is the bottom line
In my opinion, you should decide what is more important to you: portability or image quality. Remember, just sitting at your desk it is easy to say image quality over portability. Portability means simple and easy to carry around. Will you take the time to lug around the significantly larger Phantom 4 pro all the time? Will you carry a separate backpack with your drone when you travel? Will you take the time to screw on the props and unpack everything? The Mavic Pro is a simple package and you can easily take it anywhere. The Phantom 4 Pro has an amazing camera and will reward those who deal with the extra hassle and cost.