the comments on patek phillipe and audemars are on. i have a submariner and those seem to hold value pretty well, but i also don't plan on selling it - it is just a nice daily wearer for me and i'm not worried about dinging it up (but can still pull the stainless/black with a suit).
i also agree with "buy used". i got a m-serial 2008 submariner date that had been worn for less than a week and traded in for a seadweller for about $1200-1500 less than i could have walked out of ben bridge. it had all the papers, boxes, and a no-name warranty card. i also bought it from someone in tennessee so it was tax-free and got it authenticated locally right after it arrived.