I'm gonna need more than "eh", I need to know what's wrong with them so I can improve.
also
-snip-
yay third tower
The 3rd looks better. The other towers you have bases that are too large.
They might as well be a rooftop for another buidling.
A tower, to me, is something one/two people occupy guarding whatever territory they're in.
The size of yours allows 4+ more people acces at once.
To sum this up: The are too large. Scale them down and add a little more detail.
Broken wood, boards holding other beams together, wood remains, etc.
Your build is really great. It's just the towers that need improvement. ;)