Agreed. Swiftkey changed my life. Worth the tiny price tag.
I don't know how many of these are Android-specific, but:
I like ClickStats for dog training.
Google Goggles is amazing for when I don't know what something is - I take a photo of it and Google tells me what it is.
Tapatalk for on-the-go forum browsing.
Zombies, Run for some fun when I run train.
For FB, the official app is the best. For Twitter, I use TweetCaster. For Reddit, I use Reddit Is Fun.
A really cool thing about Android vs. Apple phones is that you can completely customize your home screens using launcher apps and such. I've been using GO Launcher for years and I love it. It can take a bunch of tweaking at first so if you want simplicity, stick with the base launcher that your phone has.