Amp vs Preamp which is more important?

I am considering changing my amp/preamp combination and as I think about budget, I am wondering if one of these components should get more focus. My other question is if these components, even separates can never be considered in isolation but are always part of a pair working together.

I thought there must be a thread on this, but I couldn't find it. Feel free to respond with it here and I will shut this thread down.

Thanks!