Gringotts the two lines stay side by side once inside. You miss nothing by doing express. Currently no preshows, which really diminishes the experience.
Forbidden Journey- the most recent pre-covid set up had express usually skip the dungeon. It always skips the greenhouse and the room after that. But the trade off was you viewed a separate portrait hall where you could hear better and step to the side to see the full cycle; it was also not a big deal to wait through the full show cycle in every room. Express rarely backed up beyond the last room so lots of people took their time going through the queue while those who didn’t care just walked past. Currently of course you can’t stop in queues to enjoy them anymore. For FJ, express now skips almost everything. You go from the portraits through a door that is normally closed into the last room.
MIB is not doing preshows either but if you’re huge MIB fans it is still neat to see the stuff on the walls, the break room, see the locker room, and listen to the overhead announcements that are all skipped by express.
Spiderman has two completely different queues for standby and express.
Transformers standby sets up the ride. I haven’t seen any of the movies. Every time I’ve ridden it, I either used express, single rider, or the line was short. I rode it shortly after reopening and even though the wait time wasn’t long, because of distancing we walked through the entire queue and now I understand the plot better.
Mummy sb is neat as mentioned above. E.T. standby walks through the forest and you may or may not receive a message from his friend depending on timing.
Just be aware that express for shows does not mean guaranteed entry. It means you get seated first, if you arrive before they open it to standby.
Huge Seuss fans should do standby for the trolley in the sky.