Other than Anki, clozemaster and supermemo.com are two good paid options. I'm currently paying for supermemo.com*, and the two decks I'm using for Spanish seem to be pretty good.
Clozemaster uses word frequency lists and sentences. Honestly it's (clozemaster) one of the best free SRS products I've seen for multiple languages.
I'd avoid memrise (too many horrible quality decks). Duolingo isn't bad but certainly isn't comprehensive by any means.
The reason I'm paying for supermemo.com is because it has a good quality Chinese deck and those are hard to come by. I also want to use the updated SRS algos that it uses. SM-2 is really old and does not handle skipped days well at all. The newer versions of the sm algo are much better in that respect.
Clozemaster uses word frequency lists and sentences. Honestly it's (clozemaster) one of the best free SRS products I've seen for multiple languages.
I'd avoid memrise (too many horrible quality decks). Duolingo isn't bad but certainly isn't comprehensive by any means.
The reason I'm paying for supermemo.com is because it has a good quality Chinese deck and those are hard to come by. I also want to use the updated SRS algos that it uses. SM-2 is really old and does not handle skipped days well at all. The newer versions of the sm algo are much better in that respect.