Selesnya (green/white) is one of the many color combinations available in Magic: The Gathering. There is a wide range of playstyle options in the color combination, with unique ones in just about every format from Commander to Pauper.
Selesnya decks excel at building up a board state, capable of flooding the battlefield with land and creatures. Green and white complement each other by helping circumvent their weaknesses as solo colors. It's easy to ramp in Selesnya colors, letting you play out your spells early. The combo's biggest struggle is keeping their creatures on the battlefield, as a board wipe can erase all your work with just one card if you don't have protection in hand.
7 Landfall
Thanks to Selesnya's access to green, Landfall decks are fantastic due to how many green spells are available that let you put extra lands on the battlefield. Both green and white have powerful cards with landfall triggers, such as Scute Swarm, Felidar Retreat, and Emeria Angel.
Landfall decks want to be putting multiple lands onto the battlefield a turn to continuously trigger your landfall triggers. It is not uncommon for Landfall decks to amass a giant battlefield of creatures thanks to just a few permanents on the battlefield giving you tokens whenever a land hits the battlefield. With landfall cards that give +1/+1 counters and how easy it is for green to give creatures trample, you can easily win in just one turn.
6 Sagas
Kamigawa: Neon Dynasty gave Selesnya access to a powerful archetype in the way of Sagas. This is largely thanks to both the generic Saga support and the release of Satsuki, the Living Lore that allows you to push through Sagas and replay them for value later on when it dies.
Since Sagas are enchantments, they can take advantage of Selesnya's many enchantment payoffs to let you draw cards or discount spells. This received an even bigger boost with the read-ahead mechanic introduced in Dominaria United, letting you get to any chapter of a Saga you want with ease.
5 Counters
Selesnya has a wide selection of cards that are great at spreading +1/+1 counters and have payoffs for playing with that strategy. Humans are especially strong at this, with Selesnya Humans being one of the strongest archetypes in Historic, thanks to how quickly the +1/+1 counters start spreading across them.
It's also great in Commander, thanks to cards like Cathar's Crusade, which takes advantage of how easily Selesnya can flood the battlefield with creatures. It's not uncommon for Counter decks to run a low mana curve since the stat lines of the weak creatures will continuously grow.
4 Auras
Selesnya is one of the best color combinations when it comes to Auras. Some of the best ones are available in green and white, and the best payoffs are also in those colors. Many Auras in white can extra stat boost based on the number of Auras, such as All That Glitters and Ancestral Mask. Selesnya has the most payoffs for enchantments, something that all Auras are.
Since Auras require you to cast a lot of cards, Selesnya cards like Satyr Enchanter and Mesa Enchantress let you immediately replace the Aura you had just cast. Unlike other Voltron strategies, Aura decks can offer a lot more protection and card advantage that others can't. Green has Auras that can give trample, making it much harder to block damage from a creature since it will be boosted by all the Auras attached to it.
3 Tokens
Selesnya cards are fantastic at bringing out a large number of creature tokens onto the battlefield. Green and white both have cards that can easily bring out multiple in a turn, quickly flooding the battlefield with them. Playing tokens has many payoffs, allowing you to trigger many powerful attack triggers.
Fantastic cards to include in Token decks include Rabble Rousing, Hour Of Reckoning, and Intangible Virtue. Token decks can get out of hand incredibly quickly, and unless your opponent has a board wipe handy, odds are they won't be able to deal with the onslaught of creatures. Green and white have access to mass protection like Teferi's Protection and Heroic Intervention, letting you even protect yourself from these threats. So long as your opponent(s) don't have anything with trample, this gives you a wide battlefield of creatures to block with to keep your life safe.
2 Lifegain
A staple of budget decks, Lifegain is one of the best Selesnya archetypes and often what Lifegain decks most tend to be, thanks to how many payoffs it has. White has no shortage of effects that give you life whenever a creature enters the battlefield, something Selesnya can accomplish very easily.
By adding green into the white lifegain mix, you gain a powerful ramp to make sure you can cast as many creatures as possible to ensure you get multiple triggers of your lifegain permanents. Green also has plenty of effects that benefit from you having +1/+1 counters on creatures, which the best lifegain payoffs give you. It becomes hard to take you out of the game as well, as it's not uncommon for lifegain decks to reach more than double your starting life total, if not even more.
1 Enchantments
What Selesnya excels the most at is utilizing enchantments. This archetype has so many powerful payoffs and enablers that it's the color combination many folks think of when they think of a powerful enchantment-focused deck. Enchantress is a name given to creatures that gain effects when you cast an enchantment, which is almost exclusive to Selesnya.
Enablers like Sythis, Harvest's Hand, Enchantress's Presence, and Mesa Enchantress are all prime examples of enchantress cards, with payoff examples being Sigil of the Empty Throne, Hallowed Haunting, and Solitary Confinement that take advantage of all the enchantments being played. Enchantment decks often have a handful of cards thanks to all of its draw triggers, allowing you to always have an answer or discard fodder. There are plenty of enchantment creatures, which all count as enchantments to give you a battlefield presence and trigger all of your effects.