You would set up persistence and if you want to put that information on your sitemap create Unbound Items for the historical values and a Rule that triggers every time the Item linked/bound to the Enocean device. The use the persistence methods to calculate and update the Unbound Items.
There is no “best” database for this. The only really bad choice is MapDB as it only stores the most recent value. rrd4j may be a poor choice if you want the data to be precise as it gets older. This db replaces a bunch of values with their average as the data ages so becomes less precise as the data ages. But the DB remains a fixed size.
Beyond that a lot of people choose MariaDB/MySQL out of familiarity. I like InfluxDB because of the ability to use Grafana for charting.