Well, I guess you have seen the guilds page, the fact that there are few posts there, does not mean the guilds are inactive, the posts are just to give a small description of what you can expect to find in a guild.
As you are Fyros, I assume you intend to go kami, if not, thats not a problem either, but to get the most from the game, maybe if you read up a little on the lore, so you can make an informed choice, as guilds are most often faction aligned.
Also there is the RP aspect to consider, maybe you want a guild that does/doesnt RP.
Geography shouldnt be a major factor, although you may start off in Fyros, you can travel to most areas with a little help.
I would suggest you find a guild you like and join the faction they support. You will be better off trying to contact them in-game as they may not frequent the forums very often.
There are many really fine guilds on Atys, these are listed as they occur to me and not in any other order :
Kami :
Hearts of Thunder, contact Sweetmarie, Essen or Ladydi.
Whispers of Aria, Contact Nysha, Vrixy.
Nexus, Contact Darmina, Thanatur.
Sanctuary, Contact Gymsko, Ryz.
East Dyron Swim Team, contact Ffionys.
Exodus Syndicate, contact Sherkalyn or Redslayer.
Knights Leviers, contact Entendu, Elemental.
Neutral : Fluffy Bunnies, Contact Fyrosfreddy
As I am Kami, I'm not sure of the karavan guilds, but I would recommend these karavan guilds:
Karavan : Guardians of Jena, contact Mardock, Scorpius.
Atys Ghosts, Contact Tissarius.
Flames of Atys , contact Soloreaper
Roleplay :
Zorai Guardians (High RP and PvP), contact Gorran, Myzam.
House of Etchmarc (High RP), contact Enon, Zyratuan