I play two decks in Modern, mostly. Amulet of Vigor combo, and Scapeshift.
If I disregard meta questions (for example, the fact that Amulet of Vigor is much easier to hate out than Scapeshift, for example) I'd say that Amulet is harder to play than Scapeshift, at least for me.
Both decks involve sequencing decisions- what land to play and search for with Scapeshift, what order to play lands in with Amulet, what lands to dig for with Primeval Titan, and so on. Scapeshift is more forgiving of mistakes than Amulet in my experience, and you don't need to deal with the variable of what land to bounce when you play karoos and so on.
I haven't played Pod or Tarmo-Twin, but given the fact that they're hybrid midrange-combo decks, I think they're probably more difficult to play optimally than Scapeshift or Amulet, mostly because you have the choice of whether to go with straight beats (which can be in-and-of itself difficult, because of having to leave blockers back, etc) or to focus on the combo in any particular game, and which you're going for can change during the game.
So my basic idea would be that all the decks in modern have difficult decisions at time- but that Pod probably has the most that you have to be aware of and able to judge.
If I disregard meta questions (for example, the fact that Amulet of Vigor is much easier to hate out than Scapeshift, for example) I'd say that Amulet is harder to play than Scapeshift, at least for me.
Both decks involve sequencing decisions- what land to play and search for with Scapeshift, what order to play lands in with Amulet, what lands to dig for with Primeval Titan, and so on. Scapeshift is more forgiving of mistakes than Amulet in my experience, and you don't need to deal with the variable of what land to bounce when you play karoos and so on.
I haven't played Pod or Tarmo-Twin, but given the fact that they're hybrid midrange-combo decks, I think they're probably more difficult to play optimally than Scapeshift or Amulet, mostly because you have the choice of whether to go with straight beats (which can be in-and-of itself difficult, because of having to leave blockers back, etc) or to focus on the combo in any particular game, and which you're going for can change during the game.
So my basic idea would be that all the decks in modern have difficult decisions at time- but that Pod probably has the most that you have to be aware of and able to judge.