Flybe
I use Flybe regularly from BHX and whilst 1 year ago they were awful for punctuality and cancellations, these days they are pretty good. It's been ages since I had a cancellation or delayed arrival of more than 30 minutes. I would say 9 out of 10 flights I take are now on time.
Of course you can never tell what will happen on the day with any carrier (for example BA always end up cancelling lots of shorthaul at LHR when someone jumps the fence etc), but if things go wrong I wouldn't bank on Flybe customer services being much help.