Here's something I made for a friend so he could figure out which one to buy: prices will vary a lot and are dropping because of newer models
Phantom 3 standard basic camera, wifi control, range about 3/4 mile, fly time about 20 minutes $500 ($389 on sales this season)
Phantom 3 advanced upgraded camera, long range, fly time 20+ minutes $800
Phantom 3 4K best camera, range 3/4 mile, fly time 20+ $800
Phantom 3 professional best camera, range 2-5 miles, 20+ minutes $900
Phantom 4 Redesigned shell, different camera mount, front collision avoidance, better software controls, goes faster than P3 $1000+
Phantom 4 professional 360 degree collision avoidance, upgraded camera, better software control than P4 25+ minutes fly with new battery $1500 or $1700 with built in controller
Mavic Pro does most everything the P3 and P4 do but it folds up into very small package, goes fast, 25 minute fly time. camera view slightly smaller-front anti-collision $1000
I have two P3 Professionals...but knowing what I know now, since I don't ever shoot in 4k, the Advanced is the best deal of the P3's. Longest distance (has Lightbridge not wifi)
If I were starting off today, the Mavic is SO cool....but the P4 Pro has the BEST camera of any drone under $3000....decisions, decisions.