Red/White/Blue Enchantment Control.
Enchantment removal is rare in main decks in standard right now. This allows for powerful ongoing effects, centered around Sphere of Safety and the Theros Gods to be very powerful.
Good Matches: Most aggressive and mid-range decks, mono-black devotion, mono-blue devotion.
Neutral Matches: Esper, almost mono-black control.
Bad Matches: U/W Control, Red Deck Wins.
Slow down aggressive and mid-range decks using hard to remove enchantments. Win with Elspeth, Heliod, or Assemble the Legion.
Mono-Blue: -2 Blind Obedience -2 Purphoros +4 Swan Song. Cyclonic Rift is a must counter, the deck otherwise has no juice.
Mono-Black: No side. Soul Tithe needs to be saved for Erebos if possible.
Almost Mono-Black (Splash White or Red): -2 Blind Obedience, -2 Warleader's Helix, +2 Aurelia's Fury, +2 Mizzium Mortars. As above, but Aurelia's Fury is for Obzedat, Ghost Council. Mortar's is there to deal with Blood Baron or Stormbreath Dragon if they splash red.
Esper: -3 Supreme Verdict, -1 Blind Obedience, -4 Chained to the Rocks, +4 Swan Song, +Aurelia's Fury, +2 Counterflux. Aurelia's Fury is for Obzedat, Ghost Council and as a finisher. Consider bringing in Mizzium Mortars as well for Blood Baron with Warleader's Helix going out. Must counter cards are Ratchet Bomb, Cyclonic Rift, and Merciless Eviction, counter or lose the game.
Any Aggro/Midrange: -4 Soul Tithe, +4 Boros Charm. Soul Tithe is less useful after side, and Boros Charm becomes mandatory to deal with blowout enchantment removal. If they play troublesome planeswalkers, leave Soul Tithe in and remove Sphinx's Revelation and Purphoros for the Boros Charms. If Stormbreath Dragon or Blood Baron become an issue side in Mizzium Mortars.
Red Deck Wins: -4 Soul Tithe, -1 Assemble the Legion, +4 Swan Song, +1 Warleader's Helix. Try to save the counters to keep out of lethal burn range or to counter a Burning Earth if no other solution is in hand. Try to land a Blind Obedience and extort to stay in the game.
U/W Counter Control: -4 Chained to the Rocks, -1 Warleader's Helix, -3 Supreme Verdict, +4 Swan Song, +2 Counterflux, +2 Aurelia's Fury. Best to just concede and go get lunch, however if you must play it. Swan Song/Counterflux is to primarily force your win conditions into play, countering Sphinx's Revelation or card draw is also worthwhile. Some versions may run Cyclonic Rift, this is also a must counter. Aurelia's Fury is as a finisher/planeswalker removal. Note that Extort from Blind Obedience may actually be your win condition.