I have both, Fly 5 and Hotas X.
Fly 5 is compact, he has detachable stick, and playing on it is pleasure, but it has weak buttons on head (i broke button nr2, it could be repaired with metal screw, maybe it is incidental). Throttle works softly, i like it. Stability of joy is 7/10, when you play both hands it will be OK. Fly 5 is very nice in touch. In overall it is a good joy.
Hotas X need more space on desk, it is more stable and havier than fly 5. Plasticks are more durable but worse in touch than fly 5. Playing is good, left hand on detachable throttle, keyboard in the middle and stick on right.
Playing on hotas x will give you a good substitute to 'proffesional' hotas systems.
Both are good but different. Both are comfortable. There is no option to decide which one is better. They have the same amount of buttons and on both you can map everyt button to play without keyboard.