There is a big difference in Luxury resources in Civ and some are MUCH better than others. So I made a list of which ones possess more abilities then others. This will help with comparing spawns and future city locations.

The order is based on how I observed and played with these Luxuries in games.
1. SALT
Salt is the #1 Luckiest and best Luxury resource to spawn with.
Adds +1 Food +1 Gold on the tile it's on and can spawn on Tundra, Plains,and Desert (I've seen it on grassland)
It's mostly seen in plains. The improved tile Adds +1 Food +1 Production
So if Salt spawns on plains early game the hex will provide 3 Food 2 Production 1 Gold
Can be Upgraded to provide 3 Food 4 Production 1 Gold (with use of techs and/or policies)
5 Production if on a river with a Hydro Plant.
Also can harvested early Tech (mining)
Pantheons can Improve the luxury as well Such as
Earth mother: Salt gains +1 faith

2. MARBLE
A good early game Luxury
Adds + 2 Gold on the tile it's on and can spawn on Plains, Desert, Grasslands, Tundra, and Hills
It's mostly seen in plains and grasslands. The Improved tile Adds + 1 Production
So If Marble spawns on grassland early game the hex will provide 2 Food 1 Production 2 Gold
Can be Upgraded to provide 2 Food 3 Production 2 Gold (with use of techs and/or policies)
4 Production if on a river with a Hydro Plant and + 1 more Production with Stone Works.
Allows the construction of Stone Works
Also can harvested with tech (Masonry)
+15% build speed to Ancient and Classical Era Wonders.
Pantheons can Improve the luxury as well Such as
Stone Circles: Marble gains + 2 faith

3. GOLD
A good early-mid-and late game Luxury
Adds + 2 Gold on the tile it's on and can spawn on Plains, Desert, Grasslands, and Hills
It's mostly seen on hills. The improved tile Adds + 1 Production
So if Gold spawns on hills early game the hex will provide 3 Production 2 Gold
Can be Upgraded to provide 5 Production 2 Gold (with use of techs and/or policies)
6 Production if on a river with a Hydro Plant and 4 gold with Mint.
Allows the construction of Mints.
Also can harvested early Tech (mining)
Pantheons can Improve the luxury as well Such as
Religious Idols: Gold gains +1 culture +1 faith

4. IVORY
A good early-mid-and late game Luxury
Adds + 2 Gold on the tile it's on and can spawn on Plains (I've seen it on grassland)
It's mostly seen in plains. The improved tile Adds + 1 Gold
So If Ivory spawns on plains early game the hex will provide 1 Food 1 Production 3 Gold
Can be Upgraded to provide 1 Food 1 Production 4 Gold (with use of techs)
2 Production if on a river with a Hydro Plant.
Allows the construction of a Circus
Also can harvested with tech (trapping)
Pantheons can Improve the luxury as well Such as
Goddess of the Hunt: Ivory gains + 1 Food

5. SILVER
A good early-mid-and late game Luxury
Adds + 2 Gold on the tile it's on and can spawn on Desert, Tundra, and Hills (less than GOLD)
It's mostly seen on hills. The improved tile Adds + 1 Production
So if Silver spawns on hills early game the hex will provide 3 Production 2 Gold
Can be Upgraded to provide 5 Production 2 Gold (with use of techs and/or policies)
6 Production if on a river with a Hydro Plant and 4 gold with Mint.
Allows the construction of Mints.
Also can harvested early Tech (mining)
Pantheons can Improve the luxury as well Such as
Religious Idols: Silver gains +1 culture +1 faith

6. CRABS/WHALES
A good mid-late game Luxury
Adds + 1 Food + 1 Gold on the tile it's on can spawn on Coast
The improved tile Adds + 1 Food
So Crabs/Whales early game the hex will provide 3 Food 1 Gold
Can be Upgraded to provide 3 Food 2 Gold (with use of techs)
Lighthouse Adds + 1 Food + 1 Production Harbor Adds + 1 Production Seaports Add + 1 Production + 1 Gold
Also can harvested with tech (sailing) I never get sailing early and you must build a work boat.
Pantheons can Improve the luxury as well Such as
God of the Sea: Whales and crabs gain + 1 Production

7. GEMS
A good early game Luxury
Adds + 3 Gold on the tile it's on and can spawn on Plains, Desert, Grasslands, Tundra, Jungle, and Hills
It's mostly seen on hills. The improved tile Adds + 1 Production
So if Gems spawns on hills early game the hex will provide 3 Production 3 Gold
Can be Upgraded to provide 5 Production 3 Gold (with use of techs and/or policies)
6 Production if on a river with a Hydro Plant
Also can harvested early Tech (mining)
Pantheons can Improve the luxury as well Such as
Tears of the Gods: Gems gain + 2 faith

8. CITRUS
A good early-mid-and late game Luxury
Adds + 1 Food + 1 Gold on the tile it's on and can spawn on Plains, Grasslands, and Jungle
t's mostly seen in grasslands and Jungles. The improved tile Adds + 1 Gold
So Citrus In grasslands early game the hex will provide 3 Food 2 Gold
Can be Upgraded to provide 4 Food 2 Gold (with use of techs)
1 Production if on a river with a Hydro Plant
Also can harvested with tech (calendar)
Pantheons can Improve the luxury as well Such as
Oral Traditions: Citrus gain + 1 culture
Sun God: Citrus gain + 1 Food

9. PEARLS
A good mid-late game Luxury
Adds + 2 Gold on the tile it's on can spawn on Coast
The improved tile Adds + 1 Food
So Pearls early game the hex will provide 2 Food 2 Gold
Can be Upgraded to provide 2 Food 3 Gold (with use of techs)
Lighthouse Adds + 1 Food + 1 Production Harbor Adds + 1 Production Seaports Add + 1 Production + 1 Gold
Also can harvested with tech (sailing) and you must build a work boat.
Pantheons can Improve the luxury as well Such as
God of the Sea: Pearls gain + 1 Production
Tears of the Gods: Pearls gain + 2 faith (Get this only if you have Gems too)

10. COPPER
A good early-mid game Luxury
Adds + 2 Gold on the tile it's on and can spawn on Plains, Desert, Grasslands, Tundra, Snow, and Hills. (Only Luxury that can spawn in snow)
It's mostly seen on hills. The improved tile Adds + 1 Production
So if Copper spawns on hills early game the hex will provide 3 Production 2 Gold
Can be Upgraded to provide 5 Production 2 Gold (with use of techs and/or policies)
6 Production if on a river with a Hydro Plant
Also can harvested early Tech (mining)
Pantheons can Improve the luxury as well Such as
Earth mother: Copper gains +1 faith

Thanks for reading and I hope this helps.
Comment if you disagree with any or if there are any errors.
Now hope Gandhi does not get a salt start and nukes you or worse. C: