Fullmetal Alchemist doesn't really focus on fan service like a lot of other battle manga, bust Lust probably has the biggest, I mean it's in her name. She's manipulating her appearance though so it's worth it to say that Izumi isn't too far off and at the very end of the series Winry might be bigger than both. Shout out to Olivier who might be bigger than all of them but wears a heavy winter coat making it hard to tell. Actually now that I think about it Lyra and Sloth are close too. Fuck they're basically all the same size, but I think Lust still wins I don't know.>>2252372
If you're talking about when it's explicitly stated that a woman's big chest is a good thing, then there're a lot of examples of that. Ones I can think of off the top of my head are
Lust in Fullmetal Alchemist,
Haruhi Suzumiya exploits Mikuru because of her bust,
Pam from The Office,
Kagome from Inuyasha is considered big for some reason I guess because she's only a teen,
Chun-Li's tits are ogled by the bad guys,
Power Girl's chest is impressive to many characters in the DC universe despite the comics having an average bust size of DD
Mia Fey from Ace Attorney.
Miranda from Mass Effect, Cattleya from Queens Blade makes the other girls really jealous with her massive rack,
Nami from One Piece is considered better looking after going up 7 cup sizes,
most of the cast of Monster Musume commenting on each other's busts and bodies,
Sypha from Castlevania's are commented on even though she isn't the biggest
That's all I can think of.
Fun fact buxom didn't used to mean busty, it just meant beautiful. The idea that skinny women are better that curvy and fecund women is an incredibly recent phenomenon. Tit men rise up!