It is Universal Century 0093. Char Aznable believes humanity is being held down by Earth’s gravity and seeks to end their suffering. With the help of his Neo-Zeon forces, he seeks to drop the asteroid Axis down, leaving the Earth uninhabitable by creating an apocalyptic winter; doing so will force humanity into space, the only way to truly evolve. The only one standing in his way is his rival Amuro Ray and his Londo Bell forces. Amuro must use the full power of his Nu Gundam in order to have a chance in stopping Char. History is in the making as the two rivals battle it out one last time.
The war between the monarchical Galactic Empire and the democratic Free Planets Alliance has raged ceaselessly across the galaxy for over a century, with the fleets of both powers having fought countless battles. Currently the conflict revolves around the strategic Iserlohn Corridor, one of only two passages of space through which the two forces can access each other. Here the Empire has built the nigh-impregnable Iserlohn Fortress, whose deadly weaponry has thwarted repeated efforts by the Alliance to capture her. Phezzan, a neutral mercantile state, controls the other corridor. The long war has resulted in an indecisive stalemate, but there are two men from the two worlds who will change everything: Wen-Li Yang, a gifted strategist from the Alliance who wants nothing more than to retire and be a historian; and Reinhard von Lohengramm, a man from the Empire whose ambition knows no bounds. Their loves, struggles, triumphs and failures play across an interstellar stage of intrigue, war and death.
This recommendation is based on the assumption that what you really enjoyed about all the Gundam shows up to Char's Counterattack is the Amuro-Char rivalry in the setting of an epic intergalactic war. Because if that's the case, feast your eyes on Legend of the Galactic Heroes. It promises a lot of big questions about humanity, empire, morality, the universe and everything while providing a powerful rivalry between two geniuses - Yang Wenli and Reinhard von Lohengramm - and a mahoooosive intergalactic conflict that simply dwarfs what's depicted in UC Gundam. LOTGH is more intellectual, more challenging, loftier, and sophisticated but will deliver thrills in equal measure.
Above the Buff Clan homeworld rises their complete fleet of battleships and heavy mobile mechas, dominated by the awesome majesty of their latest and most deadly superweapon. And even with all these forces, Supreme Commander Doba is troubled - he has staked the future of his entire people on this military might. Can the lethal weaponry prepared by the Ome Foundation truly prove sufficient to slay the Giant God of legend, Ideon? Meanwhile, on the Solo Ship, the Earthlings only want a planet they could escape to to avoid the endless attacks of the Buff Clan - a desire they know can never be. They cannot abandon the Ideon for fear of what others may try to do with its power, but they do not control it and its very existence among them only incites further bloodshed from their relentless foe. For the Solo Ship and the Buff Clan, the final conflict is rapidly approaching...
The epic showdown, the feature film conflagration and conclusion these two mecha franchises. Granted, Gundam continues to chug along as a franchise, but the feature film Char's Counterattack was conceived as the last word in that saga and it concludes the central narrative of the Universal Century timeline... while the Ideon film manages to conclude the saga for good in, well, a very finite manner.
Either film involves plenty of epic robot fights (moreso in Char's Counterattack), climaxes to long-running rivalries, and stuff blowing up (moreso in Ideon). Knowledge of the franchise beforehand is recommended if you want to see either film; one can probably get by on the summary feature movies if you don't want to trawl through old lengthy TV shows.