All other things being equal, shorter bows will tend to be easier to control (being shorter also makes the bow lighter than it would have been). Longer bows obviously have more playing hair length.
I think it is much harder to make an unusually long bow that plays well at the tip. Some players have a preference for these longer bows. František Pošta used very long bows by Milan Oubrecht. I am not much of a German bow players but I found the Oubrecht bow I tried to be strange, and the added inch or so of hair didn't make up for the way the foreign feeling in the upper half.
I've also played a comically short Peccate, and while it was awesome for staccato notes, it was far to short for a lot of the playing we do now.
I say, if you are shopping, don't venture too far outside of the normal dimensions.
For French, 66-68cm (stick not counting the button) and between 130-140g. This range could be extended to 125-145, but you get the idea. You don't need to get out a tape measure and a scale when shopping, just know your own bow for comparison.
I would warn against getting something really long, or short or light or heavy. You should be looking for a good compromise of features that will be usable and help you grow as a player without getting in the way.