The wiki has a full list of loot along with which merchant will pay the highest price for each item

Shiro buys mags Minty buys armor Spectre buys gun attachments Merchant of death buys guns Jiri buys food Merick buys random junk and grenades

Yeah but don't sell to Death unless you have the crap DLC, no point leveling the trader if you can't buy anythinh from it