I'm pretty jealous of the MsM event. the Boss souls and the Petite Pets look amazing!
AoT was definitely one of my favorite crossover events that I've participated in. The Battle against the Colossal titan and fighting the Titans after him was a lot of fun. Also speed running the titan training was a blast.
Honestly I would contend that marriage as a whole is utterly pointless at this stage and should wholly be removed.
With how much Onyx apples have been handed out through past events, it does feel unnecessary to get married at this point. The one chase item for the party quest has become a bit too common as an event reward.