There are a lot of nice video editing programs out there, unfortunately a majority of them come with high prices. I'd recommend Sony Vegas or Adobe Premiere, but I'm assuming you don't have or want to spend hundreds of dollars on them.
Luckily for you, there's a free version of Lightworks which I've tried and LOVE! Here's a link below:
https://www.lwks.com/ (goto the download page to get the free version, it's not a trial)
Keep in mind that you'll have to watch tutorials on how to use the program, as the layout and video editing isn't easy for beginners. Also, you don't get that many export settings with the free version.
I also think that Windows Movie Maker isn't all that bad in the stop motion department, and you can always use sound recording programs to record your voice with, and add your audio into WMM.