The camera seems very delicate on the Mavic, but the video quality is excellent, 1080P at 60 fps has some quality problems, but all other settings very good, I shoot 4K all the time, I use ND filters, on the Mavic these are tricky to fit especially as the camera is so small, but on the P4 they screw on very easily. Very hard to see any difference in video quality.
The field of view is slightly less on the Mavic, some people prefer this rather than too wide an angle of view, I hardly notice it.
Hand catching on the Mavic is not for me, but very easy on the Phantom.
A significant point to consider is the noise, the Mavic is very quiet and people will hardly notice it, the P4 is a big noisy beast and will attract attention.
Ultimately it is your personal decision, but these points may add to your decision process.
Please post your decision and your first flight experience, good luck.