Here are the summary points of which drone you should buy:
I have been getting lots of questions about which drone should be purchased and the answer has almost always been the $999 Phantom 3 Advanced or the $1259 version that includes a hard shell backpack and an extra battery. The only difference between the Advanced and the Professional is the addition of 4k and for most people, that is an unnecessary feature that I will explain.
First of all, if you have never used 4k video then you might not realize how intensive it is. You will need professional software to edit it (windows movie maker will not do it) and you will need a fast computer or it will bring it to a crawl. Another downside to filming in 4k is the low frame rate of 30 frames per second. The 4k does look incredible, but paying the extra money ($1519 for the Professional with hard shell case and battery) just does not make sense unless you know that you need 4k. I say save your money or buy an extra battery if you are not sure if you need 4k.
Should you buy the Phantom 3 Advanced or the 3DR Solo? This easily can be boiled down to an easy question of cameras. Do you want to use a GoPro or be locked into the DJI camera world? If you already have a high end GoPro I would recommend going with the 3DR Solo at $999. The other budget option for GoPro owners is the older DJI Phantom 2 at $699.
When does the Inspire 1 get recommended? Not that often for a few reasons. First of all, I have to say that I love mine. It is a beautiful machine and it flies great. However, for most people it just does not make any sense to spend $2899 when the Phantom 3 is nearly as good. What do you get for 2-3x the cost of the Phantom 3 line? A higher power machine (6s battery vs 4s battery in the Phantom 3 and 3s in the Phantom 2) that can fly faster and handle more wind. However, I put my Phantom 2 through many high wind filming sessions and it performed well. The camera can be removed and upgraded and you can use two controllers to drive the camera. The portability of the Phantom should also not be overlooked as the size of the Inspire 1 makes transport more difficult.
You should buy the Inspire 1 if you have the extra cash or you want to look more professional. It is a sexy looking drone and if you are accustomed to top of the line, you will probably buy it regardless of the value of the Phantom 3 line.