Colossi cost 25 Favour, not 60, and Zeus gathers Favour extremely quickly. If you think 5 Priests will take down a Colossi in decent time you obviously have never played Egyptian against late-game Greek before. A fully upgraded Mythic Age Priest will do 8.64 damage per second against an 1100 HP Colossi. That means it'll take more than 25 seconds for 5 Priests to take one down, by which time he'll have probably taken out two of your buildings. Let's not forget that when his HP is low he'll go and eat from a gold mine or tree and regenerate faster than you can hurt him!
Mummies are the only real answer without Funeral Rights, unless you have massed Priests but that leaves you vulnerable to all sorts of other things Zeus has in his late-game locker.
Yes, get Forge of Olympus first, but Colossi spamming is extremely effective in almost all scenarios. You can easily ensure you have enough Favour to do both as soon as you hit Mythic Age as Zeus.
Take my love, take my land, take me where I cannot stand.
I don't care, I'm still free, you can't take the sky from me.
Take me out to the black, tell them I ain't comin' back.
Burn the land and boil the sea, you can't take the sky from me.
There's no place I can be, since I found Serenity.
But you can't take the sky from me...[This message has been edited by DragonQ (edited 04-24-2014 @ 05:42 AM).]