The following is my purely subjective rankings of the factions in various categories. Generally I refer to 4 fleet types.
1. Balanced Fleets
This is a mixture of capital ships, cruisers, frigates, starfighters etc. All facitons can build these types of fleets.
2. Kill Fleets.
These fleets are all about pure firepower and are usually various types of imperial fleets or late era fleets.
3. Carriers Fleets
These fleets are usually either 100% carriers of have a handful of capital and cruiser ships (that tend to carry craft) with at least half the fleets devoted to carrier type this.
4. Super fleets.
These fleets are built around super star destroyers/Star defender ships (Bellators and up).
Generally I rate the factions based on unit roster (due to FTGU scenarios), admirals, heroes and finally starting positions on the larger sand box type maps. Gnerally I think its easy for the top 2 facitons the bottom 2 but the middle is very subjective.
Top 8 Overall
Perhaps the only outright bad faction the Yevetha do not have enough going for them. They are missing a lot of basic imperial units, have weak heroes, and only have 1 unique ships which did not even seem that good.
7. Eriadu Authority.
Tectors, Torpedo Spheres and a unique escort carrier make them very competitive. Praetors seem to have been nerfed though from 2.1 and there heroes are average at best. Good capital ship faction. Weak Admirals, a bad location and weakest Imperial on the land puts them down here.
This faction is not bad as such more average and awkward to use. Mostly ranked this low simply because the other factions are better IMHO.
5. The Empire. They start off very good with Tectors and strike cruisers with good support ships. They peak in Era 3 with XR 85's, modular task force cruisers, heroes and Sovereign class Star Destroyers. During era 3 I would bump them up to 1 or 2 and everyone else shifts 1 position down the list.
4. Pentastar Alignment.
Formally the best in the game they lost their 2 starting SSDs, they get one of them back at week 20. Compounding their problems the Praetor seems to have been nerfed along with the carrier strategy which they were the best at. They are beaten at carriers by Greater Maldrood and arguably Zsinj and they do not have the great unique units cruisers and 6 point ships (Tectors, Crimson Command VSDs, Allegiances etc) to make up for it. Still Praetors will get the job done and they get Secutors and as well as Munificent's and the procursator. Since they are basically a era 4 or 5 Empire they have been placed ahead of the Imperial Remnant
3. The New Republic.
Very good faction even inn era 1, but they take a bit to get going and their best units are era 4 and 5 where I would rate them as number 1 or 2 (1 in Era 5).
2. Greater Maldrood.
Much like the Empire of the hand, great cruisers, capitals, heavy ships, can build Bellator SSD and Alegiance and has great units to go with them. Good on the ground,
1. Empire of the Hand.
More or less blatantly overpowered on all the criteria I used. Best starting location, good heroes, great units good on land and space.
Top 8 Personal Favorites
This list is based on what factions I find fun to play, generally on admiral difficulty and on the Art of War GC.
1. Greater Maldrood
5. New Republic
6. Pentastar Alignment
7. Eriadu Authority
8. Empire of the Hand
Top 8 Carrier Factions
Well these guys can't build crriers at all and have no bomber units. At best they can have a cloud of trifoil fighters.
7. Eriadu Authority. Fairly generic units with shield equipped TIEs and no exclusive carrier units. Can spam lots of TIE hunters though they are btter used in the other fleet types.
6. Empire Better than the EA but not by much.
Gets better in era 2,3 and 4 but its mostly less awful relative to the other factions.
5. Pentastar Alignment.
Very good carrier faction, only let down on a higher placing due to 4 other factions being better. The PA is also quantity over quality with its Secutors, Acclamators and Venator carriers.
4. Greater Maldrood
Can go several ways with carrier fleets building around Secutors, ISD II's, or TIE Avengers/ARC 170's. Probably has 3 + types of viable carrier fleets.
3. Empire of the Hand
Almost everything that launches out of an EotH fleets seems good. Would be placed higher but they lack the Nebulon B frigates and underpriced Lucrehulks and Zsinj level ISD II equivalents.
Zsinj doesn't have the variety of the PA and GM but makes up with in cheap spammable TIE Raptors and the Lucrehulks. Zsinj ISD II's carry 2 TIE Raptors while quasar fires and Nebulon B offer quantity and quality.
1. New Republic
The best carrier faction in era 1 and doesn't really lose the crown although you could make the argument that in era 4 and 5 Zsinj or the EotH might be better due to the loss of the Nebulon B but they pick up E and K-Wings and various support ships so they mostly have quantity and quality in most eras.
8. The New Republic
The New Republic ships tend towards the carrier side of things and they lack the required units to make dedicated kill fleets not really picking up the right ships until era 3 or 4. An era 1-3 NR kill fleet looks a bit more like a balanced fleet and/or still has lots of X-WIngs attached.
The Yevetha only really get the Allegiances but lack the required support units such as good AA corvettes and srike cruisers to really make them shine. Still they get allegiances.
6. Pentastar Alignment.
These guys ge Praetors over Allegiances but lack a good AA unit to suport them but they do aquire procursator cruisers and Accalmators which helps and its enough to put them 1 ahead of the Yevetha
5. Zsinj. Zsinj gets Allegiances and is rich enough to afford them. He is in a similar boat to the Pentastar Alignment but has better 1 and 2 point units to support said kill fleet. Still its not really this factions specialty.
4. Empire of the Hand
While the EotH lends itself to building carrier and balanced fleets they have a good selection of capitals, cruisers and frigates they can use to cobble togather a kill fleet. At least better than the factions ranked lower than them.
3. Eriadu Authority.
The Eriadu Authority gets Praetors, Tectors and good support ships to back them up such as TIE Hunter escort carriers, tartan patrol vessels and Torpedo Spheres. Would be rated higher but faction 1 and 2 get strike cruisers.
2. The Empire.
The Empire gets tectors era 1,4 and 5 along with Allegiances Era 2 and 3, the lancer right through and Praetors era 5. They also have the incomparable strike cruiser which is the work horse of these types of fleets as the other factions have to make do with Victory/Procursator Cruisers.
1. Greater Maldrood.
Allegiance check. Strike cruisers check *2 allegiances, 9 strike cruisers is not to bad). Good AA corvette check. Additionally they get 2 more good choices of cruisers to help with the CC VSD, and the Procursator. Even the venerable VSD I and the Bulk Cruisers can be used here. If I had the choice I would probably pick Tectors over Allegiances but nothing is perfect.