The Universal situation is weird. That land is becoming increasingly outdated, especially when you compare it to what Universal's doing with Potter, Jurassic Park & probably everything at Epic Universe. So I can see them wanting to replace the Marvel land with something they could make new & fancy, especially now that Nintendo has turned into a cashcow for them.
But I get why they'd want to hold out & keep the rights out of Disney's hands too. WDW getting Marvel would potentially huge for them.
I'm not happy with either tbh. IOA's land has some great rides (Spidey in particular), but the theming is so tacky (that god awful '00s rock soundtrack, those stupid character billboards everywhere) & the costumes for the character are so cheap.
Meanwhile, Avengers Campus has slightly better theming (INCREDIBLY boring though, just a bunch of grey buildings), the shows seem fun & the characters look great. But their Spidey ride looks awful, probably the worst looking ride Disney's done since Little Mermaid.
Both companies have done great rides with the IP (Spidey & Hulk for Universal, the two Guardians rides for Disney). But they've both failed on the theming part.