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.
Show
did a tier list (it only includes the main character gundams, so as not to clog the whole thing up with the racist ones from g). top tier gundams are (in no particular order) wing zero custom ew, barbatos lupus rex, v2, moon gundam, alex, and the turn a
bottom tier is all the ones from seed, plus the narrative and the unicorn with all the lights on. what a garbage aesthetic
favorite non-gundam mobile suit is the fucking sazabi. just a perfect design, better than every gundam
We're going to need an alignment chart like the one below, but for "what is a Gundam" because if you're flexible enough the Sazabi is totally a Gundam.
developed from the moon gundam i suppose