Field Spells have been apart of Yu-Gi-Oh! since the very first Set of the game. At their release, they were rather basic, providing boosts and/or nerfs to Monsters depending on both their Type and Attributes.
Nowadays, however, Field Spells have evolved into something much more than that. They generally have more specific effects that give huge boosts to many different strategies. Many Archetypes have their own Field Spells and are so good they alone made their Deck as good as it is. Most meta Field Spells aren't generic except for a small handful. That doesn't stop them from being the best the game has to offer, however.
10 Necrovalley
"Necrovalley" is one of the oldest Field Spells in the game that are still powerful today. Originally released in 2003, "Necrovalley's" first effect simply gives all "Gravekeeper's" Monsters 500 Attack and Defense. What makes "Necrovalley" so good is its other effect, which prevents cards from being able to be removed from the Graveyard. So long as it's on the Field, cards there are permanently stuck there. With so many cards relying on Banishing themselves for their combos, "Necrovalley" is a fantastic choice to shut those cards down, and can completely dismantle the opponent's whole strategy.
9 Domain Of The True Monarchs
"Monarchs" were one of the earliest Archetypes introduced to Yu-Gi-Oh! and comes with a fantastic Field Spell in "Domain Of The True Monarchs." This card allows its user to lower the Levels of cards in their Hand in order to Summon them without Tributing, something "Monarchs" greatly appreciate.
What makes "Domain Of The True Monarchs" really good is the Floodgate effect that when its controller has no cards in their Extra Deck and are the only ones to control a Tribute Summoned Monster, the opponent can not Special Summon Monsters from the Extra Deck.
8 Numeron Network
"Numeron Network" is a card great for two things. One is to OTK comboed with "Numeron Calling," and the other is to set up "Number S0: Utopic ZEXAL." The Field Spell allows "Numeron" effects to be used without detaching Xyz Materials, which can very quickly defeat the opponent in one Turn. Thanks to them all being the same Level, after attacking (or after Summon if it's the first Turn), they can be used to Xyz Summon "Number S0: Utopic ZEXAL" which prevents the opponent from being able to activate any cards for their whole turn.
7 Dragonic Diagram
"Dragonic Diagram" is a Field Spell so good that it's currently Limited on the Banlist. Its first effect is decent, giving "True Draco" and "True King" Monsters 300 Attack and Defense, as well as protecting them from Battle Destruction once a Turn. "Dragonic Diagram" is so good due to its second effect. This destroys a card in the player's hand to search out a "True Draco" or "True King" card from their Deck. When paired with the "Baby" Dinosaur cards, "Dragonic Diagram" builds up incredible advantage for Decks that can play it.
6 Union Hangar
"Union Hangar" is support for the "ABC" Archetype, a series of Union Monsters (and the best Union Archetype in the game). "Union Hangar" does everything it needs to do to make the Archetype so good. It searches out any Light Machine Union Monster on activation.
Once per Turn, whenever a Light Machine Union Monster is Summoned, "Union Hangar" equips a different Light Machine Union Monster to it from the Deck (but it can't be Summoned). This makes it great to setup to Summon the Boss Monster of the "ABC" Archetype, "ABC-Dragon Buster."
5 Dragon Ravine
"Dragon Ravine" is an incredibly simple Field Spell, with one of the best effects in Yu-Gi-Oh! Being able to send a card from the Deck to the Graveyard is so good, "Foolish Burial" is Limited because of it. While "Dragon Ravine" is locked to only Dragon-Type Monsters, many Dragon Monsters have powerful Graveyard effects. "Dragon Ravine" also has the power to add a Level 4 or lower "Dragunity" Monster to their Hand. "Dragon Ravine" is so good since it's a soft once per Turn, meaning if another copy goes onto the Field the effect can be used again.
4 The Hidden City
"The Hidden City" is a Field Spell belonging to the "Subterror" Archetype. This card combined with "Subterror Guru" is what makes the "Subterror" Deck viable. When "The Hidden City" is activated, it searches out any "Subterror" Monsters from the Deck. Once per Turn, it can flip a face-down "Subterror" to Attack position, which is incredibly useful since most are Flip Effect Monsters. During the opponent's Turn when a Monster declares an Attack, "The Hidden City" can flip a face-down "Subterror" Monster to not just active their effects, but negate the Attack as well.
3 Lost World
"Lost World" is the premier Field Spell for Dinosaur-Type Monsters. When a Dinosaur Monster is Summoned, it can Summon a Token to the opponent's Field, and as long as they have it, they can not Target any card on the Field but Tokens with card effects.
In addition, if a Token (including the opponents) would be Destroyed, "Lost World" can Destroy a Dinasaur-Type Monster from the controller's Hand or Deck. In Dinosaur Decks, this can build incredible card advantage thanks to the ability to Destroy "Baby" Dinosaurs from the Deck that can then Special Summon more Dinosaurs from the Deck.
2 Magical Meltdown
"Magical Meltdown" is an "Invoked" support card, that also gives a giant boost to any Deck that utilizes Fusion Monsters. When it's activated, it can search out "Aleister The Invoker." The power of "Magical Meltdown" is for its Fusion Monster support, however. The activation of cards that Fusion Summon a Monster can not be negated. In addition, cards and effects can not be activated when a Monster is Fusion Summoned. This ensures Fusion Monsters can get onto the Field without having to worry about getting Destroyed or their Summoned negated.
1 Mystic Mine
"Mystic Mine" instantly warped the format when it was released. It is without a doubt the most powerful Fied Spell Yu-Gi-Oh! has ever seen. "Mystic Mine" is one of the most powerful Floodgates ever, as it completely prevents the opponent from attacking or using Monster effects so long as they control more Monsters. It's incredibly easy to set up this situation, and with cards like "Metaverse," it can even be activated during the opponent's Turn in order to completely shut down their Monsters. "Mystic Mine" is a card so good, it can win games on its own due to how insanely powerful it is.