I like seeing the characters in seasonal as it helps bring out an extra layer of charm to them and sometimes they'll reference events that seem interesting (H! Sakura talks about outrealm stuff she did with Elise)
My favorite seasonal characters are the FE7 Love Abounds Trio(Seeing these three just goof off at festival together while Roy and Lilina hang out was all I wanted in life) , Christmas Chrom (Chrom just a good man so it's always fun seeing him talk about different events), PA Azura (The dark songstress outfit is appealing to me)