On a purely objective level, probably any of the Software Toolworks/Mindscape educational games. They're not even that good at being educational, lol.
As someone who has actually played Mario's Early Years: Preschool Fun and its CD ROM collection version of the game and has explored everything it has to offer, you are wrong; it exemplifies the sheer hypocrisy of fans who go "oh why doesn't Nintendo include representation of more niche series in their spin-offs" and ignore the timeless beloved characters such as the Fun Friends and these unnamed child characters who bear an uncanny resemblance to Mario
It has creatively designed worlds such as Shape World, Opposite World (which is just a carnival theme park), and Color World (the last two levels are grocery-themed, a theme we have yet to have in a Mario platformer)
You can play as Peach and Yoshi, you couldn't play as Peach since SMB2. Yoshi is only to the SNES version of the game so make sure you get both versions to get the complete experience (as well as the CD Rom collection version of the game)/
The game has voice-overs, which has preceded every other Mario game ever.
and deep lore such as Weegee being a bus driver (if only we had a Chip and Dale Rescue Rangers-style reference and have the Illumination Mario movie reference Weegee and his bus driver occupation!)
this kid who loves the Koopas and has a picture of Icky Iggy's face in his room for some reason
this unexplored part of a location from Dinosaur Island (evident by the familiar-looking hills in the background)
and if this dude is Old MacDonald or Mario dressed as Old MacDonald.
Enjoy the horrifying stark contrasts between the two versions of this game (what other Mario game can be played on two platforms? HUH? It's ahead of its time.), because if you continue to shit on it, I'll go and play Fun with Lett