If you liked Soul Reaver (and everyone should like Soul Reaver, because it's a masterpiece
) you'll like Soul Reaver 2. It's pretty much the same but with way better visuals, as you would expect from a game for a new generation.
LoK: Defiance is a different beast, but I really enjoyed too. The game focuses on the story a lot too, like both Soul Reaver games, but this time cameras are fixed and combat is way more important. Puzzle solving is still there, of course. I really loved playing as both Raziel and Kain for the first time in the series.
It's a shame that Square has decided to abandon the series, really, it's always been one of my favorite sagas. Just imagine how a new Soul Reaver could look with current technology. If only they gave it a chance again...