choose the engine first ...There is no simple answer. Controler is just a part of power combo and
vice versa every combo is suitable for particular machine. The biggest
danger with AC controler is an "out of sync" error that is an major
failure given by the fact that controler loose its orientation
(and going to be restarted). Event the best conroler would
easily fall in such vital problem when it is connected to wrong
engine (or even worst if the engine is running in bad working point).
So, however it looks that there is no simple answer, there is one.
If you use the controler the recommended engine and run in in
recommended environment (heli) than everything will work fine without
any glitch ...
.. back to real experience - never heard of Castle Creations (I come
from the Europe), but Schulze and Hacker are both excellent. (I was flying both in different engines). I would vote for Schulze, because I am using their centrolers since 99. But as I mentioned the reliability and efficiency depends not just on the controler ....
I would be you, I would reverse the question - choose the engine first and pickup the right ESC afterwards (Schulze for Hacker or Plettenberg, Hacker for Mega, Actro-Koehler with its own control panel and so on ...)
The troubles mostly come from the "experimenting" and "tunning" instead to simply keep the recommendation of the heli manufacturer