I have found each bird has its plus and minuses.
1. Size, there are some locations where a bigger bird can be the hazard than the surroundings (Spark vs Mav Pro/Phantom)
2. Abilities, For the most part the spark can produce a very very good picture in both video and Stills (the spark takes 12mp stills, the same as Air/Pro/Phantom 3 & 4 non-pro) The only drawback, if you think 2.7k & 4k is the bees knees and you can't live without it. I put my video above (Glen Helen Park, shot in 1080p with ND16 Filter). There are other specs that some will bring up (transfer speed of data 60mbps to 100mbps) but again that is such a non starter as most people couldn't tell the difference.
3. Access/portability, The Spark fits in the palm of an adults hand and the Air when folded does also. The Pro is little bigger but the Phantom series is like check luggage at the airport. The Spark/Air & Pro line can be carried as carry on.
In conclusion I put drones in the same category as DSLR cameras and Guns, its only as good as the person behind/ at the controls of the unit/weapon.
The videos and both the stills where shot with different units
I used both the Spark, Pro and DSLR on the Hilltop video for a restaurant. The pic of the construction site was taken by the Air and the sunrise was with my DSLR (Cannon Rebel Xt)