Which are your favorite player machines with long lastability?
I am a good player and hate easy machines, I get bored immediately. Some machines are punishing and in my opinion those are also often the ones who last long in a home collection.
Basically think in the opposite direction than great machines for casual players and location. Think instead about machines for good players who want to own the machines for very long time, playing at home, alone, not trying to impress any friend.
In the end please also specify how much you like the theme of the chosen machines: just because I believe we all are very influenced by the theme (nothing bad about it), so it will help me to understand your choices.