Personally for me, the best mobile Steem app is Partiko.
At the moment, there are only two "good" mobile app for Steem: ESteem and Partiko. I have used both in the past and I can confidently say, Partiko is 90% better than ESteem (in my opinion). I would have given 100% for Partiko but ESteem has a feature that disables loading of images, which is a very good feature when you are trying to save some data.
Before Partiko was launched, I used the ESteem app to browse Steem on my phone. It was honestly full of bugs back then and crashes 3 out of 5 times when I used the app, which made me uninstall it 3 days after and just used the Google Chrome mobile app.
Months after, Partiko was released and truth be told I wasn't expecting much about it. To my surprise, Partiko loads very fast, is so smooth, and is honestly very slick. All qualities that I am looking for in a mobile app. From then on, I have used Partiko to browse Steem on mobile.
Partiko also has a point system, wherein transactions you made within the app (upvoting/commenting) gains you some Partiko points which can be traded for an upvote from the Partiko team.
I don't know all the Steem apps built for android but I have two that I use very often and I find working pretty well and being useful. I know that you asked for just one and the best of them all, but I can't stick to just one so I will talk about both of them. First is my connection with Steem when I'm mobile, the one that I am using to read articles, comment and reply to comments when I am away from my laptop and that is eSteem. eSteem was created by @goodkarma and it is the best mobile app for Steem that I have tested by now. I had partiko also installed on my phone but didn't liked the way it synced notifications and that it didn't had a night mode. On eSteem everything is pretty simple and it works almost all of the time. It freezes sometimes and it has some bugs but it gets the job done. You can post with it, although from what I know eSteem takes a share from your payouts for using its app to do that but is also gives some upvotes when posting with it and using the tag so it's a win-win situation. It doesn't drain the battery, you can choose to deactivate notifications and what I like a lot is the fact that you also have the option to set a pin code to avoid anyone from sneaking into your account. You can actually do almost anything that you do on Steemit, but on an app. Next on my best apps for Steem is steepshot which in my opinion is the perfect way to replace Instagram if you are searching for such an experience but with all that the Steem blockchain has to offer. You can share pics with your followers, upvote the posts of others using steepshot and get some friends on the way, you can give comments, reply, transfer Steem or SBD and once in a while you can even get some upvotes from steepshot for using their app and tag. It gave me some errors in the past when posting pics, but it's great. I don't use Instagram anymore and whenever I have just one pic to share that doesn't need a whole blog post that my number one option. The app is also battery friendly so you don't have to worry about that.
These are my favorite Steem android apps and my opinions of them. Hope you found them useful and wish you a great day!
I actually have three applications that I use on my phone for Steem pretty religiously:
Steepshot - This has been great for those short little posts where you want to take a picture of something and throw a quick post up. I find myself using it a lot on the weekends when I might not have the time to write up a full post in the esteem desktop app.
Lots of people are using Instagram these days and I think Steepshot is a good example of an Instagram alternative that has been built on the Steem blockchain. Why use Instagram when you can use Steepshot and earn money doing the same thing!
Partiko - This has proven to be my go-to app for replying to comments on my posts. The interface is really clean and it is super fast. It is also a great way to check my wallet and claim rewards when I am away from a browser. I am actually pretty sad that I didn't know about this app sooner. I wish I had been using it for a lot longer than I have.
It also has the ability to earn points which is really awesome. The points you can turn in for upvotes on your posts and things like that. That is a really cool concept that I think will draw a lot of users to the app.
Keep an eye out, you are going to start seeing more and more comments and posts with that little footer that says posted using Partiko.
Steemify - This app was developed by @blockbrothers witness and it is starting to be my go-to app for alerts about things that are happening with my account. I still use Gina and it is okay for the most part, but sometimes Gina goes down and other times Gina has a lot of lag.
When you are blogging every day and trying to build a follower base it is important that you have a way to know immediately when someone comments on your post so that you can reply to them and start an interaction that may lead to a new follower.
Steemify does all of that for you in a quick easy to read way. You can even add other users to follow if you want to know when someone you enjoy has posted something new. It is a great app and I really think everyone should be using it.
It probably won't be long before I ditch Gina all-together and start using Steemify exclusively.
Those are my top three, check them out and I think you will love them as well!