Mine is pic related, the Victory Gundam. What I like about it is how modular the mobile suit is. It’s the result of years of ms tech late into the Universal Century where now the Gundam is mass produced. In the show the rebel forces are shown to have a stockpile of Gundams in a bunker so they can burn through parts.
Honorable mention to the RX-79 G ground type Gundam from 8th MS Team.
My cousin had it and I used to borrow it from him along with Fed v Zeon and Zeonic Front, ZF is another gem that gets slept on, it’s like Rainbow Six but with mobile suits.