Most importantly is added some value for getting extra dragons from cards, either by creating tokens or playing them for free from hand/deck
Sam Black (any) is a former professional Magic player, longtime Magic writer, host of the Drafting Archetypes podcast , and Twitch streamer
Intellectual Offering, Blue Sun's Zenith and other card draw spells might be a good fit but you aren't going to do better than Teferi's Puzzle Box
Samut, Vizier of Naktamun wears Anduril nicely, turning your attacking Spirits into card draw elements
Legendary creatures are in their own box, since Im more or less exclusively a Commander player, and having easy access makes deck building easier
Sylvan Anthem Sylvan Anthem only buffs your green creatures, making it narrower than Gaea's Anthem, but I vastly prefer it for its reduced mana value and scry ability