According to the official manual:
"The AUTOINCREMENT keyword imposes extra CPU, memory, disk space, and disk I/O overhead and should be avoided if not strictly needed. It is usually not needed."
So it is better not to use it? Do you have any benchmark of using the implicit rowid against using AUTOINCREMENT?
As recommended in the documentation, it is better to not use AUTOINCREMENT unless you need to ensure that the alias of the rowid (aka the id) is greater then any that have been added. However, (in normal use) it's a moot point as such, as even without AUTOINCREMENT, until you have reached 9223372036854775807 rows then a higher rowid/id will result.
If you do reach the id/rowid of 9223372036854775807, then that's it if you have AUTOINCREMENT coded, as an SQLITE_FULL exception will happen. Whilst without AUTOINCREMENT attempts will be made to get an unused id/rowid.
AUTOINCREMENT adds a row (table if required) to sqlite_sequence that records the highest allocated id. The difference between with and without AUTOINCREMENT is that the sqlite_sequecence table is referenced, whilst without AUTOINCREMENT the isn't. So if a row is deleted that has the highest id AUTOINCREMENT gets the highest ever allocated id from the sqlite_sequence table (and user the greater of that or max(rowid)), without doesn't so it uses the highest in the table where the row is being inserted (equivalent to max(rowid)).
With limited testing an overhead of 8-12% was found to be the overhead as per What are the overheads of using AUTOINCREMENT for SQLite on Android? .