Hmm, I might nominate Genius, Strength and Energy – the double-resource cards – as more universally useful. Their inclusion rate is over 90% if one relies on the decklist data at MarvelDCB. That data is not entirely reliable, since it’s merely a compilation of decklists, and some decks are just meme decks. Still, it has some usefulness. By contrast, Avengers Mansion is included only around 40% of the time. Helicarrier appears about 50% of the time. So it seems a lot of people balk at the tempo loss incurred by Avengers Mansion.
Personally, I always include the double-resource cards, but I don’t always include Avengers Mansion or Helicarrier, even though I agree with Tom that Avengers Mansion is a very strong card. It’s strong in true-solo play, and I imagine it’s even more powerful two-handed. I do wish there were more of a restriction on its use, and I might say the same of the double-resource cards. Like Tom, I want as varied a “metagame” as possible.
And that’s one reason I do sometimes exclude Avengers Mansion: for me, it’s more interesting to explore alternatives. Variety is more fun. Also, I like to roleplay.
Sinister Motives does not include Avengers Mansion, and the preconstructed decks therefore don’t include it either. (They do include all three double-resource dards). So for my first play of the campaign, I’m not using Avengers Mansion. So far I’m not missing it, but then I’m playing only on Standard.
I prefer Expert myself, but I’m not sure I agree that the “real game” begins only in Expert. The winrate difference between the two is only around 8.6%: 70.4% on Standard, 62.8% on Expert. The Standard success rate is about the same as that of a MLB pitcher, and having been a pitcher myself, I still think failing 30% of the time is enough to make a game interesting! That data is from the spreadsheet I linked earlier, which has logged almost 24,000 plays, so it’s a big sample size. Marvel Champions statistics - Google Sheets
Edit: Yes, the spreadsheet relies on user submissions, but social science tells us people are more likely to post their successes than their failures. So that 70% standard success rate might be significantly lower in reality. Humans are illogical. People Don’t Share Their Failures Often Enough | Psychology Today.