Hi everyone!
For beginner photographers what'is the best drone?
  Dji Phantom 4 Pro Or Dji Mavic Pro and Why?!
Please give us some reasons!

Any of them are OK for beginners, because they all have fully automatic camera modes. But do you plan on being a 'beginner' forever? If photography is your passion, then the P4P is by far the best.

For a beginner, I would recommend you to consider Mavic Pro. It is portable and you can fly it anytime. Holding a big luggage requires to make plans anywhere, haha.  

They both have much to offer whether your a beginner or experienced drone enthusiast, you really need to decide where you would like to go with this new hobby as Geebax said.
One thing I can tell you is you won't get this technology at this price anywhere out there except dji...

I'm with Susan. I have just gone backwards from P4P to Mavic and have been flying DJI for a few years now. My habits have changed and no doubt will change again but for now it's the Mavic due to smaller footprint. Yes the images the P4P has given me are brilliant but I found I had to plan my flights more. The Mavic is an excellent machine and once you get used to manual exposures etc, it can come into its own. Beginners should also find the Mavic a little less scary than the Phantom 4 Pro / Advance and a lot cheaper if you realise you don't like flying drones after all...