If two different bikes fit you, you may find that the larger frame requires a shorter stem and, conversely, the smaller stem will need a longer stem to achieve the right position.

A short stem will typically give a faster steering response, whilst a longer stem will give a more relaxed style of handling.

So ultimately your choice will be determined by the type of handling you prefer (and, to a degree, the aesthetics of long vs short).

We only recommend stems within a sensible, useable range, so none of these are bad choices (no overly twitchy or dull handling).