yo definately soy.. I hate the taste of milk anyway.. soymilk is 100% better tasting to me.. and uhm.. also milk is sick shit.. contains cow puss.. since it's secreated through cow organ.. heh.. and they inject cows with antibiotics so they don't get sick and you get those and build up an immunity... and they wonder why antibiotics don't work anymore ;/ ... milk gives you cancer... pfft.. I don't care soy gets you ripped
I switched from skim to Soy and noticed less water retention. Anecdotally, i think its true that milk tends to make your skin a little thicker appearing. Finally, I think soy tastes better.