DH & I are a bit older than y’all and have taken every one of the tours you list except DestiNations, although I’ll admit we did Backstage Magic so long ago that two of the attractions we visited are gone now! I think DVC discounts apply to all of them. We’ve enjoyed every tour, so I’d recommend you consider length and cost as well as subject matter. Search this board & post questions to get more details re each one - the online descriptions on WDW’s website aren’t always specific enough to help in making choices.
Of the ones you listed, I liked Marceline, Steam Trains and Backstage Magic the most, but again they were all very enjoyable and interesting!