Rune Factory 3 is definitely the easiest game on that list. Nothing hard about it at all other than knowing where certain buildings/people are in the town sometimes.

Disgaea has artificial difficulty (due to needing to level up, and even during the story, you still need to level grind pretty high to beat it), Dawn of Mana's difficulty comes with the whip controls and the level resets (still not THAT hard), the Tales games can be hard sometimes, DQVIII can be broken in half and made your bitch by mid-game, but that is like 30 hours in, Phantom Brave seems pretty hard until you figure out the system, and HNV is mostly easy, but won't beat RF3 in easiness. Twilight Princess being easy depends on previous experience with Zelda games.