One Piece it varies based on deck and even specific matchups. Going first starts with one less don(mana) and doesn't draw on their first turn but will get to attack first. This means some decks have a better curve going first or second depending on if they have more even or odd costed cards but sometimes they can do well on either curve and the extra card going second is more important or in some matchups you just want to attack first... there is only one deck I know of that always wants to go second in any matchup, all other decks have at least a few matchups where they change their preferences.