For covenants, I would say the order goes something like this:
I am Holy (Blue) - Best used with silver and chamber of angels for a virtually cost free use. Super powerful card if used properly
Covenant with Moses (Gold) - either used with a speedier deck to stop writ or shroud, and also used for big NoN with moses
I am Healing (Gold) - Works great with any offense, but its very rarely used... super underrated card, Imo
Covenant of Noah (Blue) - any offense
I am Justice (Silver) - stonewall
I am Patience (Green) - stonewall
Covenant with Phinehas (Teal) - used only with priests, for obvious reasons
Covenant with Levi (Teal) - used only with priests, for obvious reasons
I am Creator (Red) - works best with an offense that needs to get specific characters out quickly, cap'n band, zeb, stuff like that
I am Love (White) - white ignore deck... pretty rare
I am Truth (White) - same as above
The other ones I rarely, if ever, see played in T1.
Curses go something like this...
Confusion of Mind (Pale Green) - Goes in every deck, pretty much without exception.
Captured Ark (Crimson) - Again, should go in almost every deck.
Unknown Nation (Evil Gold) - Goes in most decks, except for a really demon intensive defense.
Go Into Captivity (Crimson) - Defenses without warriors need not apply
Rain Becomes Dust (Gray) - Can be put in many deck types, I personally don't see it used that often.
Madness (Orange) - Goes great with orange, also useful in a deck with lots of fight by the numbers on defense
Unsuccessful (Gray) - Any deck, best with a grey defense so it can be used in battle for numbers, if necessary
Besieged (Crimson) - Any evil banding deck, philly giants esp.
Wastelands (Orange) - site lock
Blindness (Orange) - good in a deck with lots of placed cards and demons, High places. I expect this card to see a lot more use
Given Over to Egypt (Evil Gold) - egypt deck discard!
Oppressed and Robbed (Evil Gold) - egypt deck discard!
Carcasses (Black) - WoS
The other curses see little play, at least in my experience.