Moxie is probably my pick for #2 Composure behind Plucky. It in a faction that loves the pay-to-win mechanic, and it has stats that are generally very useful to those who can take it.

• Sefina is a no-brainer for Mox, as she's basically a Mystic and loves to turn those Painted Streaks into Shrivelling hits.
• Although Jenny seems like a likely candidate, she often enjoys Streetwise, which already comes with a superior booster, so you're taking Mox for the pump. If I could afford the off-faction slots, I'd sooner take Physical Training than Moxie for the complementary stats.
• Skids and Finn both make for surprisingly effective homes for Moxie. By playing either of these gentlemen, you're resigning to fail most tests. However, some are still must-pass, and Mox becomes an "in case of emergency, break glass" tool for help your Frozen in Fear and Rotting Remains woes. The booster is also welcome for either gator.
• Wendy very much enjoys this card as well. Her already good means Mox covers you for any extra difficult willpower tests, and she's obviously going to love the agility help. Wendy has access to economy like Hot Streak(2), and Survivors also don't have a ton of expensive cards to play.
• Leo seems to be least likely on this list to take Mox, mostly because he's very money-hungry and doesn't have the extra cash to fuel this. Also, his is so laughably low that he will have to pay too much during must-pass agility tests.

Overall a situational but effect tool for most investigators.