Legendary cards can be found by identifying the gold pentagon
As I warn every year, this list is entirely subjective
Most other mass removal spells in Standard right now either cost more mana, have some sort of stipulation on them that gives your opponent something in exchange for blowing up the board or just isnt as efficient as Day of Judgement

$29.99 Nyxbloom Ancient (0016 - The Cloudsea Djinn) Final Fantasy Through the Ages $59.99 Ranger-Captain of Eos (0002 - Knights of San d'Oria) Final Fantasy Through the Ages $32.99 Yawgmoth, Thran Physician (0011 - The Emperor, Hell Tyrant) Final Fantasy Through the Ages $29.99 Urza, Lord High Artificer (0005 - Terra Branford) Final Fantasy Through the Ages $6.49 Gix, Yawgmoth Praetor (0035 - The Shadow Lord) Final Fantasy Through the Ages $8.49 Loran of the Third Path (0024 - Garnet Til Alexandros 17th) Final Fantasy Through the Ages $10.99 Chromatic Lantern (0061 - Crystal of Altar Cave) Final Fantasy Through the Ages $57.99 Ragavan, Nimble Pilferer (0043 - Zidane Tribal) Final Fantasy Through the Ages $8.99 Cryptic Command (0029 - To the Crystal Tower) Final Fantasy Through the Ages $39.99 Purphoros, God of the Forge (0014 - Kefka Palazzo) Final Fantasy Through the Ages $17.99 Bolas's Citadel (0007 - Kefka's Tower) Final Fantasy Through the Ages $37.99 Akroma's Will (0021 - Blessing of the Oracle) Final Fantasy Through the Ages 0 results found

Sure, they can interact with it as it ticks up, but thats spending removal on something that isnt going to win you the game, which is bad for them