Hi, we will be visiting Warsaw, Torun, Gdansk, and Poznan by train. Would you advise, from Warsaw, going to Gdansk or Torun first, in regards to an easier transit route ?
Are you flying in and out of Warsaw? If you prefer direct trains, you could do Warsaw -> Gdansk -> Torun -> Poznan -> Warsaw. All these routes are less than 3 hours on IC o EIC.
If you are able to fly open jaw (different in and out cities), you could fly into Gdansk and fly out of Warsaw. In that case, you could do Gdansk -> Torun -> Poznan -> Warsaw.
You can check train schedule at koleo.pl. It has English option.