Your Stage : Dilemma with Two Alternate Ideas of a Single Story (I NEED HELP) by Johnathon Zimmerman

So, I'm writing a short film. Initially it started out as a scene that could potentially be the beginning of a spy thriller of some sort. But as I was writing it I began to feel like there were so many plot holes I found difficult to fill that I started to feel a little depressed about it and less confident. Tonight I had a brilliant idea to completely change the backstory. Originally it was about a washed up burned CIA Operative who is presented with an opportunity to prove his innocence. Problem is, I was having problems with plot points in the backstory. So my idea was to instead make my protagonist actually be in hiding (still a former CIA Op) acting as the guardian of a little girl who was the product of genetic experimentation. Therefore changing the entirety of the short to be more of a sci-fi thriller rather then spy thriller. I know that both stories sound a bit cliche, but I'm not overly concerned with that right now, this short is something I just wanted to cut my teeth on. Personally I feel more drawn towards my second idea, but I've already gotten so much written and put so much effort into my first idea that I feel like I should stick with it and finish it out. But I find it hard to novitiate myself to do that. Any advice, tips, suggestions, or feedback? Should I go with my interest and rewrite nearly the whole thing, or stick with what I have so far? (I'm willing to share the 8 pages I have written so far with anyone who's interested in giving feedback.)