RE: Fast 3 or Flying fish?
OK lets analyze this a little:
First the single motor airplane and what it says about it -
Automatic climb mode (likely indicates there is no elevator control at all)
Ingenious thrust vector control (likely just a limited rudder control)
Full function radio controller (Hogwash, it is a limited two function unit and from the other descriptions this controls throttle and limited rudder only)
Now to the twin motor airplane aero dynamically it could be a viable airplane except for one major problem, it lacks any form of aerodynamic controls at all None, nothing! What that two function radio does is provide collective throttle and differential throttle for steering. At best this a problamatical system.
The bottom line is neither are capable of your stated goal of 'seeing how I like it first'. They are barely capable of any control and they will not enable you to learn anything about flying model aircraft. They are toys and nothing more and are incapable of helping you decide anything.
A hundred euros or less is not going to accomplish what you want to do. Your money would serve that goal and help you realize the dream much better if you saved for the glow types or better electrics.
John