It's hard to go wrong, but the choice is complex.
Disney Lorcana: The First Chapter offers three different starter decks with their own unique styles of play, all of which can be used to jump into the game without any supplements. Limited supply for the new collectible trading card game has made starter decks particularly desirable, making it important to grab the right one when the chance arises.
One great combination that serves this goal in the Amber/Amethyst starter deck is the pairing of several Magic Broom: Bucket Brigades and Mickey Mouse: Wayward Sorcerer. Mickey can play Brooms for cheaper and return them to the hand when the cards would otherwise be removed from play, making it hard for opponents to get a handle on this novice spellcaster's mayhem.
Gramma Tala: Storyteller, Mickey Mouse: Detective, and One Jump Ahead are all key cards for ramping up in the Sapphire/Steel deck, with each offering its own method of adding to the inkwell at a low cost. Steel also features some low-level cards with combative might for an aggressive start, like Fire the Cannons! and the powerful Disney Lorcana card Captain Hook: Forceful Duelist.
One key factor of the Emerald/Ruby deck is the inclusion of five mid-range Evasive cards, unevenly split between Pongo: Ol' Rascal and Peter Pan: Never Landing. Getting these characters in play makes it difficult for opponents without the right cards to get rid of them, making it possible to rack up some lore without interruption. The opponent, however, is likely to deal with a fair bit of interruption themselves.