Which ones do you think are better? For each large, medium and small.

For the small ones, i currently have tailoring, enchanting and salvage yard for my priest (It got boosted, so i found those optional as well, since i have those 2 professions)

Salvage yard just seems strong overall, and goes hand in hand if you do follower missions.

For medium i picked the Barn to keep going with the fur, and get some savage blood eventually.

For the large ones, i created the Dwarven mill yesterday. When you look at what it does, it seems pretty decent if you can get lots of upgrades, but it doesnt seem like people are getting lots of those upgrades anyway?
I only created mine yesterday, and i upgraded it to level 2 today, so i didnt get my first badge yet. - Do you think this building is worth it to get higher iLvl gear for your followers, and therefore better gear for yourself once they get to 645?

Do you also think it would be worth it to build the Dwarven mill on my alts?

(Actually i only have the dwarven mill on my druid, which is one of my main/alts, havent decided yet) - but my spriest (currently my main) does not have the dwarven mill yet.

So should i just get the mill on all my classes and hope for follower upgrade, or should i just leave it for my druid, and maybe my priest? ^^

It seems it depends on what content you focus upon as well.

Of course, I have my professions in my garrison. My other buildings are barracks for bodyguards, more active followers, and I like gnomes protecting my garrison .^_^ Barn is self explanatory. Trading Post I have @ lvl 2 for more GR for mats that I do not use.

The Bunker is more PvE based in comparison to the Gladiator's Sanctum (I play Alliance so I don't know names for horde.) Of which is why I have the bunker. Eventually when I get enough GR, I will change Trading Post to Sanctum I think.

Pro tip you should have an inn. Inn = high GR income.

Yeah, I've been looking up comparisons. I would only get the inn prior to the Sanctum just to finish up the followers. Of which I think is my plan.

Scrapyard, Inn is nice, Enchanters study for DE.

Well worth it. I've made 2k+ resources in 1 day just from missions. With enough scavengers to counter every type, every resource mission is at least 100 resources. Most I got from 1 mission was 1190.