When we done our reviews once upon a time we did mention if a civ was particuly good at a niche or situation (seafaring island maps, expansionism continents etc). I think we made 2 basic assumptions.
1. Civs were rated at Emperor difficulty or around the middle of the road.
2. You were starting a game where the land mass type was random.
Some of the traits at higher levels of play are better while others are useless at higher difficulties and marginal even on the lower ones. Generally the agricultural, commercial and industrial traits are regarded highly, expansionist and miltaristic not so much. And then you have to consider the UU. Essentially any civ with 2/3 of those traits and a good UU is an excellent civ, 2/3 a good civ and 1/3 a weak civ as a general guideline. A particuly good UU can also drag up a "weak" civ. Trait synergy however is also important along with starting techs as Seafaring and Commercial both have alphabet IIRC.
Iroqous. 2 great trait s and one of the best UU in the game= tier one.
Celts. 1 great trait and one of the best U in game= tier one.
Maya 2 great traits, fast expanding civ but awkward starting techs and weak UU= good civ.
Zulu weak traits, below average UU= weak civ.
Very few civs are completely useless (being defined as outclassed in every way by other civs). Mongols, Hittites and Zulu are probably the closest thing to it while the Germans have kinda weak traits and a very late and marginal UU with the Americans in a similar boat but their UU is even weaker. Some civs are particuly good in their niche such as Babylon with culture, Greece with Science, and England with money. The tiers we came up with were guidelines only. I quite like the English for example even though they were rated as a tier 3 civ. There was even a bit of disagreement among the authors of the civ reviews from long ago over some of the placing the civs were rated at. From memory (I haven't played Civ III for a long time) I would rate the civs as such.
Tier One
Iroquois (Agricultural, Commercial) (Alphabet, Pottery)
-good 2nd trait
-best starting tech
-great UU
Sumeria (Agricultural, Scientific) (Bronze Working, Pottery)
-great traits
-UU average
Netherlands (Agricultural, Seafaring) (Alphabet, Pottery)
-worst 2nd trait
-good UU
-best starting tech
Celts (Agricultural, Religious) (Ceremonial Burial, Pottery)
-high priced solid UU
-CB weak starting tech
Greece (Scientific, Commercial) (Bronze Working, Alphabet)
-good 2nd trait
-good UU
-best starting tech
Persia (Industrious, Scientific) (Bronze Working, Masonry)
-great traits
-best UU
Arabia (Expansionist, Religious) (Ceremonial Burial, Pottery)
-pottery 2nd best starting tech, CB is worst
-expansionist is crap shoot (can be great or non-factor depending on luck)
-good UU but would rather pay 10 more shields for extra hit point knight
Ottoman (Industrious, Scientific) (Masonry, Bronze Working)
-great traits
-good but late high priced UU
China (Industrious, Militaristic) (Warrior Code, Masonry)
-average 2nd trait
-no horizontal research
-good fast UU
Tier Two
Egypt (Industrious, Religious) (Ceremonial Burial, Masonry)
-CB is weakest starting tech
-weak UU with limitations (can’t go thru swamp, wetlands or mountains)
-Religious can be useful tech if used properly.
Aztecs (Agricultural, Militaristic) (Pottery, Warrior Code)
-average 2nd trait
-weak UU
-no horizontal research
France (Industrious, Commercial) (Alphabet, Masonry)
-good 2nd trait
-good UU
-best starting tech
Byzantium (Scientific, Seafaring) (Bronze Working, Alphabet)
-great UU
-best starting tech
-weakest 2nd trait
Babylon (Scientific, Religious) (Bronze Working, Ceremonial Burial)
-great for culture
-average 2nd trait
-average UU
Maya (Agricultural, Industrious) (Masonry, Pottery)
-great traits
-UU average
-no horizontal research
Japan (Militaristic, Religious) (Wheel, Ceremonial Burial)
-only civ to start with Wheel which give benefit for early tech trades
-CB is weakest starting tech
-good fast UU that doesn’t require horses can defend and attack
-average traits, militaristic is other crap shoot tech
Rome (Commercial, Militaristic) (Alphabet, Warrior Code)
-best starting tech
-good UU
-traits are slightly above average together
Korea (Scientific, Commercial) (Alphabet, Bronze Working)
-good 2nd trait
-good UU
-best starting tech
Russia (Scientific, Expansionist) (Bronze Working, Pottery)
-good starting techs
-Expansionist is crap shoot that is only good for about the first half of Ancient Age
-average late UU whose special ability needs to be accompanied with artillery units
India (Commercial, Religious) (Ceremonial Burial, Alphabet)
-good extra, hit point, no iron UU
-have best and worst starting techs
-religious trait is good if used correctly
Tier Three.
Inca (Agricultural, Expansionist) (Masonry, Pottery)
-UU below average
-no horizontal research
Zululand (Expansionist, Militaristic) (Pottery, Warrior Code)
-Pottery 2nd best starting tech
-both traits are crap shoots that can be great or can be worthless
-worthless 2 move defensive UU. Only possible value to escort horseman rush?
Portugal (Expansionist, Seafaring) (Alphabet, Pottery)
-2 best starting techs
-worst trait synergy in game. Seafaring worst trait overall
-worthless UU whose special ability only lasts for about one tech (crossing oceans)
Spain (Religious, Seafaring) (Alphabet, Ceremonial Burial)
Alphabet best starting trait, CB is worst
expensive low value UU
Seafaring is worst trait
Mongolia (Expansionist, Militaristic) (Warrior Code, Pottery)
-Pottery 2nd best starting tech
-both traits are crapshoots that can be great or useless
-UU doesn’t require iron, movement over hills and mountains but would rather have one more defense point for 10 more shields
England (Commercial, Seafaring) (Alphabet, Pottery)
-2 best starting techs
-nearly worthless UU, usually build these only to set off Golden age
-Seafaring is worst trait
Americans (Industrious, Expansionist) (Masonry, Pottery)
-Pottery is 2nd best starting trait
-Expansionist is crap shoot that is only good for first half of ancient age
-worst UU in game
Vikings (Militaristic, Seafaring) (Alphabet, Warrior Code)
-Alphabet is best starting tech
-Seafaring is worst trait and Militaristic is crap shoot trait
-expensive UU, needs protected, amphibious assaults, best attack for middle age, doesn’t upgrade
Hittites (Commercial, Expansionist) (Pottery, Alphabet)
-crap shoot 2nd trait
-best 2 techs to start with
-good value UU
Carthage (Industrious, Seafaring) (Alphabet, Masonry)
-good high priced UU
-best starting tech
-worst 2nd trait
Germany (Scientific, Militaristic) (Warrior Code, Bronze Working)
-late average UU
-average 2nd tech
And this is only a guideline. Germany and England could be tier 2 just because I can find 10 civs that are argueable worse, and I'm short of a civ for tier one so Babylon Egypt or Maya could be bumped into tier one (at the bottom of the tier but tier 1 is the best 10 maybe 11 civs).