I believe Bloodborne is considered the easiest if you have a PS4, I don't. All the Souls games have active communities on PC so they will all will have people available to summon, but Dark Souls 3 will have the most active community obviously.
Well, DS1, not so much. I mean, it could have a active community if the online worked properly, but Namco left it utterly fucked after the Steamworks patch.