I'll actually nominate the account that brought me to Steemit @aflfantasy

It's a fantasy sports based account, hosting a season long competition in the Australian Football League run by @o07 & @dahmsy79 - the same type of competition I have been involved with elsewhere as well.

It's been a fair bit of fun and will enter again next year (though I'm still a chance to make the Grand Final if I can upset the undefeated league leader this weekend).

But without this account, I would likely never have heard of Steemit, and probably wouldn't have joined, so without this account I wouldn't have had the chance to "meet" some amazing people from all over the world.