I love GC3, and at this point it is way more enjoyable than GC2. One thing though is missing that takes away from the game for me; the economy. In GC2 you inevitably will have times where you will go bankrupt because of how fast you expanded to keep up but I have never gone into the negatives in GC3. I haven't played that much, but it seems like I also dont make as much money as was possible in GC2. But you cont even change tax rates, which is a huge dissapointment to me. I do have founders edition, so I would be thrilled as Im sure many other players would be if the first expansion included an expanded economy system.
You can't change taxes, no, but you can change how much of each output a planet gives (click "Govern"), which is very similar, and trust me when I say this, simply allowing each planet to put out 33/33/33 is extremely weak compared to their output at 100% of a single factor. If you specialize a planet's buildings and set one output to 100%, it can do the job of half a dozen planets that try to do everything at once. If you do this, though, your Manufacturing and Research planets will not be paying for their own maintenance, so you will go negative FAST unless you get some Income planets online.
I'm guessing that's what you're looking for, so try that. I warn you, though, it's addicting, and you WILL run out of money very quickly. 
