I watched all the episodes of Attack On Titan and I'd say WiT was better with Sakuga, they were great with camera movements and that it had great contribution to the popularity of the series in a way a Mappa production wouldn't achieve.
But for my personal taste I like the work of Mappa just as much mainly because I always felt like WiT's work looked too glossy and plastic for me to truly fall in love with it (especially in season 1)
Just because one style makes a show more popular doesn't mean that it appeals to my tastes more.
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