I guess it all depends on your expience with BMI Baby, I know people who have experienced delays but I have flown with them 12 times over the past 18 months and can't complain about the service at all.
I was delayed once in Prague due to bad weather but many other airlines we also affected that night, we were given food and drink vouchers very promptly and kept as well informed as you ever are.
So based on my experience I may have voted for Baby.