If you have a limited lineup definitely don't get AFM when you already have MM. You have the 90s represented.
If money wasn't an issue, I'd go for JJP's POTC and Elvira's House of Horrors. And a JP if you are getting 3 more.
More generally, I'd say get 2 newer Sterns. If you're going for 3 more games, 2 Sterns and a JJP.
For JJP, try POTC, Dialed In, WOZ, or Hobbit if you like long-playing games. a regular Hobbit or Dialed In will be way cheaper than POTC.
For Stern, take your pick. There's a lot of greatness in the top-15. JP, Metallica, Iron Maiden, Deadpool, Elvira, TMNT, Star Trek,and heck the new Avengers Infinity Quest looks great too. Those are all just incredible machines, regardless of if you get a Pro or an LE.