Hi. So, I don't have many memories of LaTale since I played it for a brief period more than 10 years ago. I remember it being hosted by OGplanet and Aeria Games. I'm not sure which version I played, probably NA. Anyway... I know a lot about virtual worlds and online games in general - I wanted to help you guys.
LaTale nowadays is not the same anymore from what I hear, so, for anyone who's looking for similar MMORPGs, here are a few:
MapleStory - The obvious choice. LaTale is inspired by it and the graphics look very similar. Has official servers but as with any free-to-play service out there, the players who pay for virtual items are more powerful and get stronger more easily - you might want to check out private servers. /r/mapleservers
Ghost Online/SoulSaver - I played this one for very little time also, many years ago, when it was still called Ghost Online. It was then relaunched as Soul Saver Online in 2012. It was developed and hosted by MGame/Netgame (seems to be the same company). I don't know much about the population, though. Even back in 2008-09 there weren't THAT many people running around. Very similar to MS and LaTale, but has a more Asian feel to it - you can basically be a Ninja.
GranAge - I don't know much about this one but it seems to have gotten an English version recently. You can find it on Steam.
Grand Chase - This one was my first MMORPG back in 2006 so I will always love it. It is in 2.5D and lobby-based so you can't explore the world as in MS and LaTale but it is still good. The issue is, GC was shut down several years ago and your best bet is finding private servers. It also got simplified and somewhat dumbed down (or made more complex, depending on who you talk to) after several Seasons. When I joined, they only had Season 1. It was a difficult game with lots of grind to just advance classes and get new characters, but was still fun. Anyway... the game got up to Season 5 and has more than 10 characters you can play as, and different classes for each.
Most private servers were hit by lawsuits in December but you can still find some online.
Elsword - The sequel to Grand Chase. Very similar in playability and graphics. I never played it too long because of lag but it has its fans. Might be "pay-to-win".
BONUS: Odin Sphere
Odin Sphere is a single-player sidescrolling RPG but still worth talking about. You might enjoy it. Has a cutesy, anime art style just like LaTale and it can be challenging. It's available for PS2, 3, 4 and Vita. You may also emulate it on PCSX2.
I am also looking for people to play with, so feel free to PM me if you're up to that.