I'd heard of @Steem-Plus in the past, used it for about 10 minutes then gave up because I didn't trust it. I've used it again this past week and I've gotta say, I've fallen in love with it. It has some great features that I love and I think you will too.
Source
Human/Spammer/Bot Clafficication
They have a great feature that lets you classify users as humans(good users), spammers (bad users), and bots(bots). I checked mines out, and I was mostly human.
Not everyone is a good cookie though, some users have a heavy spammer count.
This can be particularly useful to see if a user throws the same comment everywhere or if their comment is actually genuine if its something thats borderline.
Voting Amount
When you vote, you truly don't know how much its going to affect it for, but this extension changes that. If you have the voting slider unlocked, right under the % is the amount the vote is going to be worth. This can be particularly useful if you want to give someone a vote worth a certain monetary amount but don't know what % you'll need to vote at to give them that much.
More Accurate Reputation
Not everyone cares about reputation, but I do. I like higher reputation as it makes users seem more trustable because they had to raise it that high, and are less likely to be spammer. On steemit, you just get a reputation with no decimals, but with the use of this extension, you get to see a more exact reputation score(though not the raw non-logarithmic score).
Beneficaries
Adding beneficiaries to post hasn't been the simplest thing to do. The average user doesn't know how to do it, and even only know how to do it with some code, still no easy way. But this changes all that. It gives you a little space to add in people you want to set as beneficiaries. I'll be testing it out by having @master-delegator(one of my projects) be a recipient from this post.
Update: I didn't know this as of posting, but they do take a 5% beneficiary. I don't know if its only when you use their beneficiary features or if its on all posts, but just pointing that out. I'm willing to pay that for their great features, but I personally think it should be mentioned somewhere near the beneficiaries button as I didn't know about it beforehand and would have preferred to know.
Preview to the right
I added this in later because I only saw this as I pasted what I had written locally onto the steemit editor. The preview on the right is similar to hack.md, so I really like it. Its a lot easier to look at it on the right, and still be able to write and see changes live.
More Features
These aren't all the features, just a few of my favorites, check out this link for all the features: https://github.com/stoodkev/steemplus.
If you would like to install it, you can do so on from the chrome webstore: https://chrome.google.com/webstore/detail/steemplus/mjbkjgcplmaneajhcbegoffkedeankaj. It says its also available in Firefox and opera, but I don't know where to find those.
All images not cited under them are screenshots taken on the steemit website with the steemplus extension added.