Cool that you're liking it. The early albums up to Dynasty are definitely the most essential but even those are iffy. What you really want is Alive and Alive II. Every song on there destroys its studio counterpart. There's a lot of other great (and good video/audio quality) concert videos that are also worth watching.
After Dynasty there are still a few albums that are worth hearing. Elder is their attempt at being taken seriously by critics. The sentiment isn't great but ironically the album is. Creatures of the Night, the followup, is kind of a back to roots effort to win back the fans they lost with Elder. Released in 1982, it takes on the early 80's metal style and is their heaviest album so far. Some real gems on there. Lastly, I'd totally recommend Revenge. The heaviest Kiss album, and my personal favorite. It's awesome.