I have and use both the Spark and Anafi, but for me they are very different tools used for different purposes. Anafi is a 4k quad with much longer flight times. It is also much larger and requires a controller of some kind to pilot (even if it is your phone). Spark on the other hand, is much more portable and suitable for selfies. My Spark is more of a travel companion for me, whether it be out on the golf course, kayaking with the wife, a quick run to a local pond to go ice skating, etc. I take it with me in the Hermit Hardshell travel case and it fits anywhere. Hand gesturing piloting means I can pull it out, power up, hand take off in a matter of seconds and I'm taking video in Active Track mode before my wife of other golf buddy has even selected a club and hit her/his next shot. No fuss. If need be, however, I can get some VERY good vacation aerial photos and videos when using the radio controller. I am not a fan of piloting with my phone. Flight times are pretty limited.
Anafi, on the other hand is a far more suitable quad for cinematic videos and photography. She is an absolutely pleasure to fly. I get about 25 minutes on a battery and, with three batteries in tote, can be out for an afternoon of movie making. However, I would NOT want to bring Anafi on a round of golf with me -- too much fumbling around to get her up in the air and taking pics/video.
(My Tello gets me through the long winters of the Northeast when you cannot as easily or often go outside and fly the Spark or Anafi.)
I've heard it said that the Spark is the only camera drone that most people will ever need. I don't think I can disagree with that. I happen to be fortunate enough to have an understanding wife that allows me my hobbies and so I have more than one drone because I want them. If pressed though, and could only have one, I am probably choosing the Spark because of:
1. Portability
2. Versatility (while not 4k, Spark takes excellent pics and videos); with the separate controller, you can still send the Spark far and high - not AS far as Anafi, but far enough)
3. Cost (heaven forbid I lost my Spark, it's a little less painful to replace than Anafi).
4. Extra batteries are 1/2 the price of Anafi batteries (but 1/2 the flight time).
Those are my thoughts from my perspective. This is obviously a very personal choice based upon what YOU want to do with your drone.