My "low G rule", which of course I keep breaking, is:
Soprano (or sopranino) = re-entrant (high) g
Concert = dealer's choice
Tenor = Low G
I keep my electric soprano uke strung with low g
Preference depends a lot on style and sound. The songs of the 20s and 30s sound best to me when strummed on a high g soprano. Modern pop songs, written for guitar, sound better to me when strummed on a low g tenor or concert.
BTW, I'm pretty sure that IZ played a tenor... it only looks like a soprano because he was so big. I've also read online (but can't confirm) that he used a standard set of high g strings, but liked to use them sequentially from thick to thin, so that he used the C string as his low G.