DS1 is starting at Papplewick in September, we know many families whose boys have been there and lots of experience of boys from both schools through DH's job. Both plenty academic (just taking Eton KS awards, last year papplewick had 2 out of 14, summer fields had 1 - previous year 3 from SF, 1 from PW, etc). About the same size but the day/boarding balance is different - PW is 55% day across the school with mandatory weekly boarding in the last 2 years only, whereas SF is only 20% day and full boarding for most.
PW strikes me as comfortable, lived in, quirky, funny with the whole snake/lizard thing, rare book club and very much encouraging boys to have a go at everything and develop their own sometimes odd interests. No flashy swish facilities though the new boarding house certainly looks like it will be lovely and cosy (cosy could describe the whole school in fact). Very low staff turnover which is always a good sign!! SF was certainly more beautiful, more polished, the boys I know from there seem to be uniformly lovely, clean cut, well mannered and clever and perhaps less oddball than some of the chaps I've met from PW. Both have good sport though SF arguably produces a few more top sportsmen, both have great music - I know music scholars from each.
If you have the choice of both I'd choose on the basis of the boarding, the distance on the bus if they are to be day boys, how much you prefer eccentric vs smoothly well rounded and comfortably cosy and lived in vs bucolic and polished, and and at least for PW whether or not they are keen on snakes and lizards!! Since every time DS1 has gone in whether for an interview or settling in day he has been handed a ball python to cuddle...