I always shut down fully.
I remember my laptop had problems with standby that I could never resolve, it was very slow after waking up even if I left it for an hour or so to run the sleep from its circuits.
Seriously, standby made my laptop very slow and waking from hibernate took as long as a cold boot.
Hibernating on this computer is only slightly faster than a cold boot, not tried standby.
I don't think any power saving modes would benefit me personally anyway - if my computer's on I'm using it, if not I turn it off.