Playing a bit of Gaia/Oranos lately...i find that Oceanus is actually a BETTER Choice in the long run then Prometheus or Leto...now if u can choose prometheus against another Kronos or Oranos do so...but if not against those 2 civs..i would Reccomend Oceanus...if u pass on Oceanus..it might not be wise.
1.Remeber..Weightless Mace..and Bite of the Shark are the ONLY Myth Techs Atlanteans get for infantry in the whole game..Boosting Katapeltes Speed and Attack and Bite of the Shark Increases Murmillo attack...very nice Upgrades.
2.Calidara-Very under-rated in my opinion...Atlanteans only real way to "Heal" since Mythic rejuvenation only effects myth units and Herioc Renewel only effects hero's..With Proper Micro..u can beat out your Opponenet "Cost wise" due to you being able to heal your army..where as your oppoent can't..Plus they are great to park outside your opponents goldmines since they also "Fly"the more units u can heal..the less money u spend..the less money u spend on replacing troops..the more money u can spend on econ and military upgrades and be ahead of your opponent.
3-Carnivora-Very under-rated...as a matter of fact..if placed properly..it can save you...did u know Carnivora do "Crush Damage"...cast it right next to an opponents TC when attacking it...it will fall alot faster...Carnivoa is "GREAT" to cast next to your goldminers...especially against Norse...since the plant will automatically swallow any cav that get close...and only Archers or Hero's can effectivly Fight the Carnivoa..anything else doies horrably if it gets to close...think of it as a better more localized version of "Plague of the Serpents" and on water this GP rocks..plus the Servant is a decent fighter and can heal your ships.
Speaking from a "Gaia" point of view...best way to beat Kronos or Oranos..is to pick and choose you battles "Carefully" until u hit herioc..and always pick Oceanus for classical..since Kronos/Oranos will always go with Prometheus..which is a waste if they can't end the game in classical...as Valor is useless later in the game..and no military upgrades..while with Oceanus..u get better Katapeltes and better Murmillo's..Follow that with Rheia in Herioc for the Archer tech..and your have outclassed him militarily..Gaia is the "Stongest" Atlantean civ from Herioc on..if u can reach Herioc with Gaia..u will "Steam Roll" Oranos and Kronos...especailly if u choose the Oceanus/Rheia Combo...why Rheia? the Behemoth.."True Siege" they are great meatshilds that regenerate and they trash buildings...Gaia also has better econ..once in herioc...Gaia's Econ blows away ORanos and Kronos's Econ...
Did u know that Gaia has arguably the "Best" God tech?
Channels-This tech is awesome...Atlanteans have the "Slowest Villes in the Game" did u know after researching Channels..Gaia has the "Fastest" Villes in the game...thas right Gaia Villes with the Channels upgrade are Faster then norse,greek,and egypt villes...it is a must get tech...as your villes are faster which means..it's harder for Turmas to hit them..and u can run from point A to point B faster which saves ALOT of gathering seconds...and ville lives
Just pick and Choose your battles in Classical with Gaia..upgrade towers early...Advance through Oceanus..and force Oranos/Kronos to fight you under your tower/TC fire and go Herioc...where u can over-power them with "Superior Econ" and "Superior military" thanks to the Oceanus+Rheia or if u like Cav..Oceanus+Theia route...if against Kronos Rush...this is the build to use with Gaia..go 1st 4 to food, 1 to wood, 1 to gold build temple in their somewhere..no econ techs and advance..Gaia forest means faster wood chopping...a 3:30 advance matches Kronos and u can get your counter-rax in position to get the Turmas pumping towards his temple sooner..it has been working for me..if u know the Rush is coming..match Kronos Advance time..remember..your window to stop him is while his counter-rax is being timeshifted gives u time to outnumber him