As a side note, Carthage seems to be doing pretty well now, building cities all over the Western Mediterranean.
I'm seeing a lot more cities being settled by all civs. It's nice to see. I do see the occasional "junk city" but they're mostly well placed.
the Seleucids and Ptolemys also seem decently balanced.
Agreed here. Pre-150 BC balance is pretty solid. Roman stability issues and the Gallic, Pontic and Dacian expansion in the wake of a weak Rome lead to wackiness by 1 AD. Things completely jump the rails by 100 AD due to Rome's failure and later civs failures to wipe out older civs, like the Kushans. Also Indian civs somehow end up conquering all the way to Ancyra!
As for early game aspects left to fix before getting to fixing those issues:
Antigonids probably still need some work. Their enemies have a very hard time dislodging them from Tarsus. They also could still use a push westwards, to form Macedonia (with Athens).
Maybe more of a mid-game issue, but the Romans have no luck against any AI civs, except maybe Carthage.
Numidians are too strong for Carthage at the moment, completely wiping them out (they should only be that strong in relation to Carthage after being weakened by Rome).
Parthians are still generally pretty underwhelming. It has less to do with the Parhians themselves, and probably more to do with the strength of the Seleucids and their phalangite cavalry-killers.
On a more positive note, the barbarian pressure in every region seems to be just right (at least in the early to mid game, which is as far as is "balanced"), so good job on that one. Map size probably helped. Perhaps a little strong in the Caucasus for the Armenian AI to handle, but that's about it. Most other civs' loss of cities to barbarians seems pretty fair.
Edit: Plains tiles are only providing one food instead of one food, one hammer. Is this intended?
Also, balance seems to be doing a lot better since the latest update!
15 AD:
We see that Numidia is still a little strong and that Romans are doing better, but are still a bit lacking. Parthians doing a good job, and the balance of the area in Pakistan/Afghanistan etc seems pretty good (i.e. barbs/Sakas doing a good clean-up of the area but not coming off too strong). Ptolemids doing well enough despite a few (reasonable) struggles, like the loss of Alexandria is this case. Seleucids pushed back to Syria very well. Antigonids doing well, but only because Romans don't bother them. Armenia is also doing a fair job.
The Seleucid balancing might also be tweaked with a little bit more revolts past the 200 BC date. This would help Parthia without an overpowering buff, and would also challenge the player a bit more. I find that as the Seleucids, aside from the GG goal (which was hard due to the GG rate), after the empire is acquired, the game goes into easy mode and I can completely crush all opposition with a large army of hoplites/catapults. Keeping an empire should definitely be military-focused and require tying down troops in Seleucid for suppressive purposes. The Romans will also come into play once they get fixed though, so that should probably be fixed before touching Seleucid balance again.
Another Axum spawn (15 AD):
Numidia still too strong. Romans doing much better. Egypt doing poorly (a bit too poorly, probably). Parthian-Seleucid dynamic is once more pretty good (again, the issue is lack of Roman pressure). Pontus and Armenia playing smart. Sakas and barbs again doing a good job.
I'm guessing the projected increased GG rate going to help the Romans a good deal, what with the free stacks it gets.
Loaded up some Byzantine games for fun...
1) Satavahanas actually founded Islam!
2) Roman stability is a major issue. They gradually collapse into nothingness (maybe because there are no Roman Rebels)...most of the time, the West is mainly the Gauls with most of Western Rome's territory, Numidia with Africa, the Sassanids with the Levant, Anatolia, Thrace etc (which is totally fine: without the presence of Rome, that probably would have happened!), and sometimes an unusually strong Judean Empire.
3) Especially in India and China, we get huge 10-20 population cities that are mega-productive/rich...(hence the founding of Islam)
4) New civs spawning in the Indian or Chinese regions seem to be overwhelmed by the older civs they're supposed to replace!