Voted for Musing.
Musing, dPoll, Busy and Steemhunt.
eSteem or Partiko, if you use a smartphone/tablet.
eSteem can be good for older versions of Android, while Partiko requires at least Android 4.2.
Musing (a Question and Answers platform) is a great way to interact with the community, and to build your Steem Power. Musing is curating questions and answers, and if you write useful/helpful answers, you will get (good) upvotes from Musing and from other accounts/users. This is the easiest and quickest/fastest way to build your Steem account. Or at least that I know.
Musing does not take any beneficiaries, dPoll does take some. This is why I recommend Musing first. But dPoll is also good for account building.
You can get good upvotes from @dpoll.curation and from other accounts/users for creating polls.
If you use Busy, and you use the "busy" tag, you get upvotes from @busy.org and/or @busy.pay. Nowadays I usually receive upvotes from @busy.pay.
The value you get from their upvotes is depending on how much Steem Power your followers have. The more Steem Power they have, the more value you receive with the upvotes of Busy.This will become useful/helpful after you get some followers. Interacting with the community is a good way to get followers.
Interacting means upvoting posts/comments, commenting (replying/answering to posts/comments, Communicating with others. A lot of people are forget this. And this is why a lot of people are leaving Steemit. Because of the lack of real interaction.
Steemhunt is good for discovering/sharing interesting/cool products, devices, softwares, games.
If you find/discover an interesting/cool product, device, software, game (and if it is not already shared by someone else), you can let others know about it by posting it, and you can get upvotes from Steemhunt, but I currently don't have personal experience about this, because I only started using Steemhunt today. I posted my first hunt today. There are some guidelines about posting, and moderators are manually reviewing (approving or rejecting) your hunt.
If they approve your hunt, you will receive an upvote from Steemhunt.