Thanks for chiming in guys. I think I'm going to buy a license of TimelineFX this month as it seems to fit my demands very well.
I did some research and found a few things I want to share:
There is another Particle Emitter called Particle Illusion http://www.wondertouch.com
However it seems that it does not get any updates anymore and it's pretty expensive.
Then there is Popcorn FX. The editor is free but does not support any rendering as far as I know.
It's very powerful but you need to bake your stuff and then plug it into either
Unity or Unreal Engine. To do so you must buy licenses http://www.popcornfx.com/pricing/
Hope that helps someone out there