No idea what max is but I'm playing on aion classic kinah buying Siel server on Aion Classic and it's super active during the day and in the evening (I'm NA East). It's fun and it's a hugely populated by EU as well as NA players. I recommend you join us. :
I chose to not join following further research, due to the organization behind Aion. I'm not able to catch up, i'm not an expert, and it's going to be a nightmare trying to win.
Asmodians can also be a problem for Elyos a lot in Heiron Some go as in the direction of ganking those who are farming Aether in the vicinity of the gate...Some gank you when you are at half health from mobs that pve you, or when you're fighting a mob. If you were to gain an advantage, why not benefit from it.
Retail was literally turned into something completely different. Everything you used to play as a child remains there. I wouldn't recommend it. If you're interested in the changes/happenings I've listed the events in my comment history.
Classic is a good option however since there are only two servers, they're still in a state of balance. Siel is more popular and asmodian heavy. they control the majority of the abyss, which can make it difficult to farm AP occasionally due to it.
Israphel has lower pop, but is more heavy on elyos. They control about 50% of the abyss, and the remainder is split between balaur, asmo, and balaur, making it much easier to mine AP. I'm NA however I play during EU periods, and though it can get a bit quiet, I've never had too much trouble in finding groups.
Tbh, Israphel is kinda dead. AP farming there is much easier because forts are more than just a few clicks away. But, the same 5-6 players will be on the job around the clock to feed guards making it difficult to farm AP in the lvl 45+ range.
Exactly why I'm trying to breath some life into it. There are at the very minimum forts to be captured or lost, but all I've learned about Siel is that the asmos hold an iron grip and won't let anyone go until they can take a look at a later date.
If that wasn't enough evidence that there were cases in which individuals were unbanned due to being falsely flagged as having multiple repeats within the same run. NCSoft should not ban only one or cheap aion classic kinah two people, and then ban all others.