TheI finally watched The Illusionist, and was struck by how the atmosphere linked back to the Triplets of Belleville.
The two films share an extreme amount of elements: they're noughties 2D animated films set in the fifties, they have no relevant dialogue but aren't silent films, they're quietly funny but pervaded by nostalgia for a time that is gone. The protagonists in both films are aging people driven by their relation to some young person. The films look extremely similar, being animated in the same (sixties-ish) animation style. This is not a complete list.
And I really can't compare the two films to each other, because the atmosphere they evoke are so, so different. For all its sentimentalism, the Triplets is a comedy. It's all caricature; character design and plot are blown so far out of proportion that they toe the line towards the absurd. For all it's bleaker elements, it is silly. It's purpose isn't to evoke thought, it's to do brilliant animation.
The Illusionist, on the other hand, ends with the only clearly articulated words in a film full of gestures and simspeak: "Magicians do not exist". There is no exaggeration in this film. The secondary cast is kooky comic relief, but there is nothing at all over the top about the main characters - their troubles are very human and completely devoid of nefarious mafia plots. It's a sweet story, and it i's profoundly sad.
While the Triplets is all "it used to be better before", the Illusionist is just hour and then some of things being past their peak. Both films are about entertainers who have fallen from a past glory, because technology and changing trends have rendered their shows unwanted. The Triplets are cheerful, eccentric, poverty-struck ladies performing in a restaurant. The Illusionist is a dignified gentleman living hand to mouth and performing in a chain of increasingly pitiful variety shows. The Triplets persevere. The Illusionist pawns his top hat and releases his rabbit.