I like to play Reiklanders, and I think they're fun to play because while they seem like generic humans, they actually have the most variety. They can use nearly all the weapons, they can shoot well and they can fight well, and they can use nearly every hired sword.
Additionally, the models are easy to obtain and/or proxy and the Empire Militia Boxed set can cover all your needs. In summary, they're a well rounded, highly customizable warband that has an answer for every problem thrown in their way.