On iOS, I like Tusker which does both Mastodon and Pixelfed in one app, and/or Ivory just for Mastodon, or Vernissage for just Pixelfed with a minimalist images-only view.
edit: I also use mona. I have trouble deciding between them because of the differences in ease of 1) switching accounts, 2) accessing/modifying lists, 3) accessing/modifying hashtags, and 4) how much of 2 and 3 sync globally to your accounts instead of just being in the app