[morganb]

If possible always leave on good terms. My background is Engineering and as a matter of professional pride I always want to say after each project/job I have done the right thing by all as much as possible. This included delay of start of another job to tie up a major project milestone. That in itself ended up having another company who heard about that come up and offer me a role.
Not all companies treat their people like crap, depends on the Management and many other factors.