I struggle to see why people who choose OAA over CTC. The hold pool/placement scheme puts you in a far better position to obtain a job; most people who complete the course do obtain employment. Don't get me wrong, I’m not the biggest fan of CTC by a long way and I deplore the way they treat some of their customers but you can’t deny that they do what they say.
I also agree with Pushkovinator, take time to visit both placed but be aware that open days or ‘careers events’ are a carefully designed sales pitch – don’t fall into the trap. Make sure you can see through the glossy marketing. I imagine both schools have their positives and negatives, but no one has trained at both so you won’t find an unbiased opinion.
I can only talk about CTC. I found the ground school tuition in the UK not to be too great, but CTC are aware of this and are working on it. There is one ground school instructor in particular who is excellent, and another who will literally bend over backwards to help you. He was often found in classrooms at 11pm helping cadets and always arranged sim rides for us too. A top bloke. In NZ you are assigned a ‘primary instructor’ who you should do most of your flying with. I like this system as it provides good continuity, your training is clearly documented and the structured program makes it easy to see what you should be achieving in each lesson and makes it easy to plan ahead. The instructors are a mixed bag like any other place, some are excellent, some are terrible, some are just rude and the whole spectrum in between. It must be said there is some excellent flying in NZ.
I think the twinstars are reliable; the diamond DA20 katanas out in NZ certainly are not. It’s pot luck whether you can start the thing... The accommodation is pretty good quality, although the NZ accommodation is in the middle of no-where and there is a ridiculous policy of sharing cars which makes it awkward to get anyway – often you can be left stranded at the accommodation.
I would strongly advise you apply to all tagged schemes before going down the self-sponsored route as you will have a far higher chance of getting a job.