Not alternatives as such, but did you know there are some really nice webcomics on here?
These are well worth a follow:
War and Peas@warandpeas
@switchingsocial , don't forget Pepper&Carrot by @davidrevoy and Cut Time by @Juby
@switchingsocial forgot to mention Pepper & Carrot
mastodon.at is a microblogging site that federates with most instances on the Fediverse.