With respect to @gruber, the best Mastodon app is on Android.
That app is Fedilab.
That's because Fedlab is not a mere Mastodon app but a Fediverse app.
Why is this important?
Because a basic premise of the Fediverse is that apps should talk to each other.
And thus, a *great* client should be able to talk, not just to Mastodon servers, but Pleroma, Pixelfed, Peertube, and Friendica too.
Just like web browsers interact with diverse websites, a Mastodon client should talk to diverse servers.
Now @gruber may say, "Mastodon is the 800 lb. gorilla in the Fediverse ecosystem."
Maybe, but it's nowhere near as dominant as many believe.
According do fediverse.oberserver, there are 21,723 Fediverse instances -- of which there are 11,944 instances.
That means there are 9,779 instances that are *not* Mastodon.
By ignoring all those non-Mastodon instances, 3rd party client devs are ignoring a huge amount of potential in the Fediverse.