Managing Key Value tags on rows

What is the most efficient way to model key value tags on records. The keys
and values will be variable and changing over time. The values may be of
various types (numbers, dates, strings etc). There will be filters and
group by selects based on tag names and maybe even tag values.

Postgres gives me the option of using hstore, JSON or just a linked table
with all the keys and values and I am wondering which would be most
efficient in terms of SELECT speeds. The writes are done in batches so this
is mostly for analytical purposes.

Thanks.