LFs <- LRFs <- Corvettes <- Flak <- LFs

Like before, LFs are countered by LRFs...this is a pretty hard counter, one of the harder ones in the game...

The new ships, corvettes, counter LRFs...of the 4 early game counters, this is definitely the softest...be wary of trying to counter illuminators with corvettes, especially if you are Vasari...

Flak counter corvettes hard...this is probably the hardest counter in the game (flak vs. fighters is the only one that might be harder)...if microed really well, flak can go toe to toe against LRFs...

LFs counter flak very well...in pure LF vs. Corvette fights, the LFs tend to win by an appreciable amount....

Generally speaking, early game fleets are either LFs and/or Corvettes or LRF+flak....there are advantages and disadvantages to each, as well as faction peculiarities...

In general, LF+Corvette fleets are stronger on a per cost basis but LRF+flak fleets are better on a per fleet supply basis...this makes LFs and corvettes more desireable at low fleet supplies (and therefore low maintenance) and LRFs and flak more desireable at mid fleet supplies...

LFs and Corvettes are faster....corvettes also are great against caps, titans, and constructors...LRFs are slower but better against structures and SBs...flak are expensive, take longer to build, and can't focus fire on high value targets, but they provide the hardest counter in the game and will be necessary to protect titans from corvettes (which are immune to titan abilities)...

Most TEC/Advent players do LF spam, incorporating corvettes as necessary if the enemy starts bringing out LRFs...Vasari players tend to either do corvette spam and attempt an orky rush or go straight for the LRF+flak fleet composition...Illuminator spam is a little strange, as once the enemy has a large amount of them you are generally better of simply trying to outspam them with your own LRFs than "countering" with corvettes (in small numbers, illuminators are still hard countered by corvettes)...

HCs counter LFs, LRFs, and flak rather well, but are more vulnerable to bombers....they are more resilient to titan/cap AoEs but also are easier to counter with support cruisers (Hoshiko's dem bots, Domina's suppression)...

Flak counter fighters hard...corvettes counter bombers alright, though require micromanagement sometimes to do this...

Fighters counter bombers, but not very well...late game, fighters are best way to counter corvettes (since flak will die to titan AoEs)...so in late game, corvettes <- fighters and bombers <- corvettes...

You could say that....

Rome 2 Total War comes out in September.....Seleucids aren't a playable faction though...

I have a funny suspicion that they fully intend to have them in-game, but they will be a DLC...

They are the perfect candidate for a DLC anyway....them being playable is not instrumental to the initial release at all, but they easily can be very popular and thus people will rush to buy them...

I hadn't thought about that but you're right. Hey, why release a full game when you can charge people more for what should have already been included! To be sure, The Citadel DLC for ME3 is okay with me (tons more content way after the release date) but Day 1 DLC really annoys me.

Hmm, for singleplayer, in the middle and late game if you build many heavy cruisers and carrier cruisers, you cannot fail.. Heavy cruisers generally counter everything in large amounts (they doesn't really have damage penalty against any ship type), and AI never builds enough bombers to be a threat against these if you have some fighters. Heavy cruisers are good against things that are resistant to bomber and fighter fire (from your carriers), like support cruisers, flak frigates and light frigates, and en masse they are good for taking out bigger objects, AI always fails against heavies, even if you somewhat rush them, the early game fleet composition is useless against them and you will win battles even in 1:4 or funnier fleet ratios, due to AI  not liking bombers much Generally they are best against long range, and AI likes to build many of those. Oh, and they can take some punishment too, like titan AoE's or capitalship AoE's so even good for taking out high level objects or super fortified starbases. Bombers are good against large objects and can be kited so your carrier ships never get attacked directly if you move them around, and fighters can deal with bombers, corvettes, fighters and long range frigates, and can easily snipe constructor frigates.

The above is not working well against humans, because they know heavy cruisers fail miserably if large amounts of bombers are deployed, and your losses will be huge (but as mentioned above AI never goes bomber heavy, only in the extremely late game with strong economy when you have your strike craft anyway to take those out ..)