I like an empty thread list
1.9: Social or Guild, depending on whether you want to include some outsiders. I prefer social for flexibility. Possibly also a separate thread for a higher rate for buildings your guild considers worthy of extra help (but really the benefit from this is not that big imo).
Battleground: Guild, let people know what's going on there
Info thread(s): Guild, Rules/FAQs/Events/Links as needed
Chitchat: I like letting the main thread at the top of guild be used for this purpose, but a thread in social instead can help keep old friends not currently in the guild part of the chat as well. And if your guild has way too many threads it may be hard to keep a battleground thread at the top so sometimes that takes over the main thread and you need a separate one for chitchat.