I've heard good stuff about all of Jeremiah Savage's KORE packs, though I don't own any.
I use KORE mostly for designing my own stuff from scratch. It's just a super clean way to be able to layer multiple instances of any combination of instruments, from any number of software makers, into a single preset that can be tagged and recalled later in a snap.
I will typically run KORE as an AU inside Live, Logic or AudioMulch for capturing my audio. Another neat thing which comes in surprisingly handy is the built-in step sequencer and arps. I keep a template preset with a series of C's and F#'s for when I want to generate a quick multisample set. I grab the audio in one shot, which gets dumped to AudioFinder, which splits it up for me, does pitch detection and names them automagically. Very helpful.
Mostly I just really love being able to have a single database for all of my instrument/fx patches. Well almost, it can't save the native proprietary devices from the likes of Logic, Live or 'Mulch - but you can get around that to a degree in some of them with saving channel strips etc.
Anyway, thumbs-up for KORE. Turned out to be a great investment and just kind of gets out of my way and helps me keep busy.