Let's discuss what everyone will be doing for their Garrison in a PvE setting.
Personally, I'm going to be with the following...
Small - Salvage Yard, Profession 1, Profession 2
Medium - Lunarfall Inn, Barn
Large - Barracks, Dwarven Bunker
Salvage Yard = More changes at items that increase item level of your follower weapon / armor.
Lunarfall Inn = Recruits 1 follower each week, you can specify traits and abilities.
Barn = Gives access to raid stat food and http://wod.wowhead.com/item=118472 at level 3 to craft the items needed to upgrade crafted gear from 640 -> 655 (Example: http://wod.wowhead.com/item=120264 to upgrade a 2/3 Darkmoon trinket, which requires http://wod.wowhead.com/item=118472 x15)
Barracks = Unlock Scouting missions and increase maximum active follower by 5.
Dwarven Bunker = Work orders has a chance to reward items that increase item level of your follower weapon / armor. Also, a chance of Apexis Crystals from work orders.