low bar is the style used by PLers and for the vast majority of people it's the stronger of the two. Partly due to shorter ROM (most can't get ass to grass in the low bar position) and partly due to greater posterior chain recruitment. oly guys generally train the high bar style, whether that's ideal or not is debatable.
either one will get you strong like bull, though.
It sounds like you don't quite understand the low-bar position though. Do you own SS? Read up on this part. In the low bar position, your arms aren't supporting the weight. you're merely pinning the bar to your back. Thumbs should be over the bar. If flexibility is an issue, you can simply widen your grip.
It should look something like this:
With the weight lower on your back, you'll naturally have to sit back more into your squat to keep balanced, and from there is where you'll really develop hip drive.