Shared Topic: Best Grind

This week's Blog Azeroth shared topic is "Best Grind", put forward by Kallixta of Kallixta's Notes.
Normally the words "Best" and "Grind" are not found this close together and there are plenty of grinds to hate. However, I'm interested in the flip side:
Was there something that required sustained and prolonged effort that you found interesting or rewarding? Was there something that was not just a chore to work on?
I'm assuming most grinds are for Reputation, but maybe you have a novel definition?

I saw Akabeko of RedCowRise had done it, and I wanted to write one as well, so I jumped on the bandwagon, as I haven't really participated in many of these shared topic blog posts.

Now most people hate the grind.  The daily grind, the reputation grind, the profession grind... but I am one of those crazy people that likes to grind, even though I don't enjoy every grind there are some which I did enjoy more than others.
  1. Fishing - I love levelling my fishing.  I have never hated fishing.  So levelling fishing was never a chore, I happily sit there fishing while I'm reading the paper, or chatting to guildies.  With the amount of fishing I do now, I could probably level another 10 people to max fishing.  Even getting the coins in the fountain wasn't that painful, it was actually more painful to watch everyone else get it before you.
  2. Archaeology - levelling arch is not a chore, I actually found it quite enjoyable and exciting.  Grinding the achievements however was not so enjoyable.
  3. Frostwolf Clan - back in Vanilla when you could only get the Frostwolf mount by being exalted, I actually enjoyed doing AV back to back to get my reputation to exalted.  Perhaps it was also because it was a group thing, lots of us were doing it together and PVPing as a group is always more enjoyable.
  4. Back in Vanilla I did like getting my Argent Dawn reputation, handing in scourgestones.  I think because the instances themselves were part of the 0.5 Tier and I was always looking for specific drops from bosses (like the bunch of flowers from Headmaster!).  I don't even know how you do Argent Dawn reputation these days.
I hate to say the "back in the good old day" things!  Was reputation better in Vanilla?  No, just those two I mentioned.  I remember grinding Timbermaw and Thorium Brotherhood and BOY were those horrible.  Now Thorium Brotherhood is so much easier with MC being a cakewalk!

So tell me what was your best grind?