I like to use busy.org for posting. It has a great range of additional functionality like the slider, notifications, voting power indicator, vote amounts by users on posts. The UI is nice and clean. Plus it has the busy upvote which is a nice boost.
I still use steemit.com for transfers, the SBD / steem exchange and anything financial.
SteemPeak looks like a great new addition with lots of interesting tools. The dashboard in particular is cool and the ability to choose the time of the post.
eSteem Surfer is one I still have to check out but I know there's been lots and lots of development recently.
The pace of development and new platforms has really stepped up in the last few months. I think the competition will be great for Steem in general.