Coincidence. I really really wanted to buy the 42. Went to the apple store, tried on the 42mm and immediately thought it was too big. Wanting to overcome my initial impressions I thought "maybe its because I was wearing the 38. Maybe I can get used to it!"
The apple store employee ended up asking three of his coworkers and they all said I should get the 38 as the 42 was way too big :l
My wrist is 155mm. I was distraught. But seriously, it really was too big.
Hm I mean go with what you like! But with the 42, there was still some wrist space above and below the watch body and with the 38 there was too much if that makes sense.
It really comes down to what the person purchasing likes. A group of strangers on a message board are going to have biased opinions.