I hire allot of people... It's always better to get a job while you have one...
I always (even if unfounded) consider an employed candidate more attractive then a on paper equal unemployed candidate..
It may be psychological but somewhere in your head you think the employed person is a better get...
I would (no offense intended) question the decision making / critical thinking of a candidate that quit a job without a new one lined up...
Good luck with you employment.. keep your options open and your decisions sound and you will be better off in the long run..