I confess I don't have that problem, but nor do I think it should be a problem! I suspect it's an avoidance strategy? After all, if an idea excites you and you start writing it then the appeal of it should grow . . . my advice is to choose the one which most appeals and ignore the others!
I have a very broad idea of where I want the book to go, then just let the characters sort it out amongst themselves. I'm not saying this is the right way to do it - some writers plot very carefully, and their books are great, but others, like me, leave it to instinct.
I think this is very common, and it's also very debilitating. I remember feeling exactly the same when I wrote my first book - I thought the style was terrible and no one would ever accept it. What I did (and I recommend this) was to copy out three or four pages of a published novel that I liked - I typed them (back in those days I wrote on a typewriter) so that they would look exactly like my own work. I then shoved them in a drawer for a week, then took them out and read the pages and thought, omg, this is terrible! But it was published and successful, so it taught me that I was being far too critical. Besides, that first draft is meant to be rough - it's the undercoat, not the finish coat. The first draft is for getting the story right, most of the good stuff comes later (and is much more fun to write).