My observations; all from Tough games, mostly small and medium galaxies with a few larges and tinies.

The Terrans are good expanders, but don't militarize much. Or at all.

The Drengin are a bit slower at expanding than in DA, but just as aggressive. I thought they were a threat then, I think they're a threat now.

The Altarians aren't THAT fast at expanding early on, but they get extreme colonization techs pretty quickly. They get planetary invasion, but seem as reluctant as the Terrans to build an actual military.

The Arceans are slow expanders due to their -1 speed and their tech tree, but they do build a military fairly early on. I haven't seen them become one of the top races.

The Torians are incredible. Real fast at grabbing planets, with Super Breeder giving them a powerful early economy. They build vast amounts of tiny ships early on. They even get Aquatic colonization early due to their tech tree, usually giving them even more planets. Usually VERY powerful.

The Yor have potential sometimes, and other times they just flop. I've seen them never getting any planets outside their home system, and I've seen them grabbing the most planets of all the races. They do militarize, although not to the extent some other races do. And their super ability is bloody annoying.

The Korx don't grab a lot of planets, and like the Altarians, they build transports but no armed ships. And they often get much of their empire culture flipped by the more expansionist races.

The Drath aren't too fast at grabbing planets, and not too fast at militarizing either - but unlike some of the other races, I've actually seen them build armed ships. They're dangerous because of their super ability, but once you can get to them, they're fairly easy to wipe out.

The Thalans are even faster than the Torians at grabbing planets, but don't like building an early military. In fact, in my last game, I let them live because I thought they never built one. About five years in, they researched weapons, and already had large hulls. I don't think they're very dangerous - they're great for an early conquest though.

The Iconians handle themselves a lot better than in DA, poor bonuses aside. They're decent at planet grabbing (their super ability probably helps), and they do build a military. Still, they're not threatening, but a pretty balanced opponent.

The Korath are just as threatening as they were in DA. They store large amounts of spore ships (although they don't put as many engines on them as they could) and have the potential to build incredible militaries, especially when they get Ion Beam techs. Yet they're not as aggressive as they could be early on. Still, they scare me enough to leave them out of the game much of the time.

The Krynn are fairly good at expanding, and fairly good at militarizing too, although they seem to stop at small hulls with the basic weapon that researching space weapons give them. It's annoying to share a border with them because of their influence bonuses. I don't think they're as powerful as they were in DA, but a fairly balanced opponent still.

Whew, that's a wall of text.

I've only played one ToA game since official release (played a few beta's).
Going to go pure on the official release game:

Huge, abundant everything, tough.

The Drengin were a threat, I suppose, but Tough isn't really my difficulty level so I might be off, was just doing a testrun. They had captured considerable territory in the colony rush and were developing a military like they should.
Then I killed them.

The Krynn are more annoying, their initial colony rush was pretty strong, but not impressive, but their second wave of colonies was huge and fast, I only beat them to most planets by a few turns. Their influence and bonuses makes them strong, I made them my ally.

The Terrans have a nice influence, they are also pretty warlike in my game. Their colony rush was okay, but not shocking.

The Yor captured an "okay" territory. They have the best ships in the game (after mine, the Drengin are dead so can't compare to them) and their Super ability restricts me to a more cautious invasion tactic. My own influence always leaves a few of yor planets outside their super ability, so not too much of a pain.

The Altarians are okay, they expended pretty well, considering their starting location, though I did get the impression that the original colony rush was a tad slow. They keep up in military quite well, but they're also my allies so it might just be 'cuz I ain't killing them, so to speak.

Iconians: Breakfast is ready! They had a poor starting location, so that might be it. But they still seem to lack any backbone.

Thalans, okay colony rush, but nothing like the drengin or krynn. They seem okay, but were quickly crushed by me. The yor are tougher.

The Arceans: colony rush means nothing to these people, they serioeusly lagged behind in that respect. I had to save them (diplomatically) from both the Altarians and the Krynn, they only survive against the Terrans because Krynn territory is between them, being patrolled by Krynn and my ships killing all humans.

I am playing as the Korx. The Drath, Korath and Torians aren't present in this game.

Hmm you've had this too huh? After five years into the game, the Krynn AI has a 172 planet empire and seem to be in great shape except for all their hundreds of ships being smalls or tinies with one or two attack on them. I was hoping it was just a rare occurrence.

I was wondering if it might be the same deal with the occasional race never militarizing at all. I played a game where the terrans had the biggest empire on the map early on but never built any attack ships and surrendered 3 turns after the drengin declared war on them. I have seen other races with similar behavior so I do not believe it to be exclusive to any particular race. The next logical conclusion for me is the research bug thing.

From a new player perspective with only cursory previous experience in DL
Arceans, Yor, and Altarians are complete garbage. Korx aren't much better. Arceans have a huge fall from grace from DL to TA from the few games of DL I saw.

The standout powerful races are the Korath and if allowed to tech the Iconians, although with the latter it is probably because I edited them. I don't know about the Drengin, maybe as I've been playing as them, and I have yet to fight the Terrans, who are indeed widespread, rich and weakly militarized, probably because by the time I get around to them I'm kicking so much ass I'm bored of the game.

I think with the new patch the strange behavior with building no ships may be gone. I played one game with 9 opponents and everyone built ships.

I don't really get the Korx. They are supposed to be mercanaries&traders. They are evil and everyone seems to declare war on them. Often evil races are limited to 1 trade route.

You would think they would be neutral and sit on the sidelines and trade and build ships. They would sell these ships to races who are fighting each other. Or if paid enough they would go to war.

Beats me. Does anyone actually play as them?