"Spark = instagram, mavic = YouTube"
I disagree. Highest res on YouTube is 1080 which both can do
4K is great but only needed in some rare situation...
I have used both mavic and spark, and frankly you can't tell the difference at 1080
This video includes Spark, Mavic and Phantom 2 GoPro 4 footage and while the P2-GP4 footage can be spotted i can't tell the difference between Spark and Mavic even knowing which is which.
The Mavic has far superior video capabilities.. it just does can't sugarcoat that. The Mavic 4K video reduced to 1080 will carry far more detail than the Sparks 1080. Again that's just a fact.