1. I assert that in order for there to be a true destiny, it would have to be sentient. If destiny is not sentient, than it is merely a perspective that, without any sort of predictable direction, makes no difference. The only thing worth knowing about this theoretical entity is its motives, desires etc. As a perspective, destiny is something that we can only know once we have survived it. In this sense destiny is simply "the past" and it really makes no difference if it exists or not. I suppose it is possible that certain truths may be shown to us after death (if indeed there is an "after death"). Destiny is merely relative.
2. Thus I may or may not be the unwitting puppet of an all powerful omnipotent pan-galactic entity.
3. If I am, I really don't want to know about it. I am perfectly happy to think that I do things because I want to do them and not because Xemu(TM), Lord of the galaxy commands me to.
4. On the other hand, if my every move were controlled by Xemu(TM), Lord of the Galaxy, I would by inference actually BE Xemu(TM), Lord of the Galaxy. That would be a fairly impressive thing to put on a resume.

Or, as a third option, maybe the path of events is determined by the laws of nature, in which everything has only one corse to follow. A hypothetical all-knowing being would be able to tell what would happen next, but could not change it-- even if such a being existed.
Numbers 2, 3, and 4 still hold.
While destiny is driven to acheive an end, this other type of unfree will is is driven from a begining... Or not. But driven from a past, at the very least. I'm not sure what you'd call it. Determinism or fate, maybe.

Or, as a fourth option, maybe there's a lot more randomness in the universe than we like to think -- and not just coin flipping randomness (after all,that's little more than rocket science), but complete, unpredictible randomness. Given a complete description of everything in the universe, and every force acting upon those things, and all the rules governing these, maybe a calculation of the future must still be indeterminate, because some things happen without any cause.

See The problem of freewill.