This question usually opens up a can of worms, I have been told that Stapleford often gets considered a bit of a 't-shirt and jeans' type of a flying school. Not that this is a bad thing, I know a guy who went to stapleford for his CPL/IR then did his MCC at Oxford, as Oxford has better facilities to cater for the MCC. Had no problem getting a job straight out with Ryanair.
I am at Oxford, speaking to Ryanair they told me that seeing Oxford on the CV puts a tick in the box for them and they do like people coming from there. But then they were doing a seminar at Oxford at the time so maybe they were just saying that you don't know.
Cabair only do Modular at Bournemouth, I considered them but being so far away it wasn't really an option.
Also Oxford will send you to Arizona for your CPL/ME, you CAN do it in England, but take into account they only have 2 warriors in total at Oxford (they have like 40 in Arizona) so that might make your CPL take a bit longer.
Airlines do want continuity with training though, they prefer what they call a 'One stop' modular course basically so they don't have to goto a million different FTO's to find out what kind of pilot you are, if they can just have one report from one flying school they seem to like that.
As far as quality in training goes don't think there is much major difference between Stapleford and Oxford, not heard much about Cabair, I have heard Aeros in Gloucester are very good.
The one thing I would say as far as Oxford is concerned is you are put into the airline mentality from the very start each flight is done as if its a commercial flight full mass and balance and passenger briefings/ take off briefings for each flight plus being around alot of other people doing the exact same thing gives you the motivation to continually push yourself to make each flight perfect.
But I don't know, alot of people on PPrune slate various FTO's due to one bad experience they have had, probably best to ignore if you go and have a look around at each FTO, check out their aircraft how many students they have per instructor etc and how many aircraft they have if they have alot of students per instructor or alot of students and not many aircraft you might find yourself on the ground pissed off alot so watch out for that..
Don't know what else to add :S good luck.