PostgresSQL if the service needs close to 99.999% availability, or more than 1 Gpbs of bandwidth or if the database is expected to grow larger than 100-200GB.

256GB means the SQLite DB can fit in RAM, or the migration will be too slow for the sqlite file and block the service.

It's important to note that with the advent of DuckDB, Parquet and Apache Iceberg, tehre are less and less reasons to stuff your main DB with timeseries data and instead only keep some kind of materialized view and send the raw data to S3.

For everything else, SQLite.