Another analogy would be this:
Most people consider the Rolling Stones' albums from 1968 to 1974 to a winning span of albums--All excellent.
These albums are:
Beggar's Banquet (1968)
Let It Bleed (1979)
Sticky Fingers (1971)
Exile on Main St. (1972)
Goat's Head Soup (1973)
It's Only Rock N' Roll (1974)
Now, it's pretty much the consensus that those albums represent the peak of the Rolling Stones' career. But that's 6 albums there. If you have 6 albums of about equal quality...It's hard to tell which is the best. Some prefer Sticky Fingers; Most love Exile on Main St and feel it's the Rolling Stones' best album EVER. As such, Goat's Head Soup and It's Only Rock N' Roll are considered great...But not as great as Exile.
Likewise, I feel KQ's 4-8 are a string of the series' best entries. Most people consider KQ6 the best of the series; I personally prefer KQ5. And I think KQ7 and KQ8 got the shaft because they weren't KQ6. It doesn't mean they're bad games, but it's hard to follow up what most people consider is THE BEST.
How can you outdo what most people have decided is the best? It's incredibly hard to, ESPECIALLY if you're dealing with a closeminded fanbase.