Pls read the link I've posted in the previous page. The intention is to have a good design, and why it is great is already presented there.
I did read it. It's very well-written, but I disagree. I think that wanting each tree to be able to stand entirely on its own is an arbitrary goal rather than inherently good design. It's not BAD design (though I find it rather redundant), but it's not necessary. The goal of having a variety of economies and paths to victory IS good design, but there are several ways of accomplishing it.
Also, I think the idea that any real-world civilization has focused ENTIRELY on one branch of endeavor is a narrow view of things. I would have characterized the Italian city-states as combining civics and diplomacy...and Venice (for instance) also had a substantial navy, crewed by residents not mercenaries.
Why limit yourself to five? If you balance for the case in which everyone pursues *two* tech trees, you have 10 different combinations, each of which would play differently. Designing in the expectation of the trees being combined in various ways increases variation.
We have different ideas of what would make for the best design. Hopefully we'll both enjoy whatever gets released 