ranks as of summer 2014

Stormcloaks- really exclusive, only pulls Nords from Skyrim.
Empire- has a lot of chapters in Tamriel. So it is good nationally
Thalmer- As big as Empire, but no where near as respectable
Companions-really athletic pulls from all over Tamriel.
Forsworn-Been here as long as the Nords. Bunch of party animals who have decent numbers and get pretty chill guys.
Bretons- really smart, needs a lot more people or they won't be here for long.
Blades- get guys who didn't get into the stormcloaks and can't really go anywhere else. They are very uninvolved.
Dark Brotherhood-Just came back, and trying to fill with respectable guys.
Khajit-barely holding on, don't even have a mead hall.
Falmar-lol, unhygienic snow elves.