I say it comes down to

1) How comfortable are you with burning bridges
2) How many days of holiday do you want before your next job
3) How soon does your new employer want you to start
4) How responsible are you with handling over your tasks to your colleagues
5) If you company practise leave encashment and if so, do you prefer to leave work early (for longer break) or get a small bonus from the unused leave

That's all i can think of for now...