Most readable way to display key value pairs
I am designing an app which has lots of data on any given screen, I've search Google and UX stack exchange and can't seem to find anything (perhaps I'm phrasing my search term wrong).
Is there any research into best practise for displaying a list of key value pairs?
Approach A - right align keys, left align value
Key: Value
Longer Key: Value
Short Key: Value that could be long
Approach B - Left align keys, right align value
Key: Value
Longer Key: Value
Short Key: Value that could be long
Approach C - Left align both
Key: Value
Longer Key: Value
Short Key: Value that could be long
Approach D - something else?
I'd be interested to know what the anecdotal best practise is here, and bonus points for actual research/testing of the best approach.