After the hell we just went through with the Maloofs and Seattle, these are truly first-world problems to have as Kings fans.
That said, it's got to be Reke - his prime coincides directly with that of our other cornerstone pieces, as opposed to Iggy, whose age dictates we win right now.
And if I'm Iggy, I make the re-signing of Reke a prerequisite of signing with the Kings, because we're a substantially weaker team without him. That is, if he cares about winning alongside getting the big money.