I don't think it's really fair to rate the 5 post 1997 albums against the 5 80's albums. These are different people, Mac sings differently and they approach songwriting differently (really since the Grey Album). That was a whole different band in the 80's. You could actually argue that the post 97 line-ups were several different bands but lets just split it down the middle even-steven and compare the last 5 albums against themselves.
Rate the post reunion albums:
1997 Evergreen
1999 What Are You Going To Do With Your Life?
2001 Flowers
2005 Siberia
2009 The Fountain
Here's mine in order of preference from favorite to least favorite:
Evergreen
What Are You Going To Do With Your Life?
The Fountain
Siberia
Flowers
I have to be honest it was a real toss-up on how to rank Siberia vs Flowers. I think Siberia was a better sounding album overall and Flowers just sounded unfinished to me. Plus I really really hate the cover of Flowers. Worst Bunnymen album cover ever. Worse than The Fountain but to be honest other than Evergreen, which was just a play on the Crocodiles cover, all the post 97 covers are pretty lackluster for any band.