JL VS Steppenwolf was fine before Superman showed up
X-Men VS Apocalypse was amazing, other than there should be more melee fight.
The Trinity VS Doomsday was cool to watch but there were too many energy blast not enough melee.
Avengers VS Thanos was cool, but I think the fight in Infinity War was better than Endgame because not enough teamwork and many heroes were not in their best form.
If it counts: X-Men vs the Sentinels in Days of Future Past. Great mix of mutant powers + my man Colossus gets some shine + they all fight to their dying breath, because they lose in both major instances until Shadowcat pulls the time travel phasing stuff.
But top dog is Avengers on Titan vs Thanos in IW. I enjoyed Endgame more, but IW was like live-action no holds-barred anime with MCU characters.