Hi,
First of all, sorry if I talk rubbish. A day on the beach and a few beers are taking their toll! Anyway, here's my two pence worth. I'm sure someone else will tell you I'm talking rubbish (this is pprune after all)
Employers do look favourably on a single training provider. Particularly if they're well recognized. I would strongly recommend it for anything after the PPL. Before the PPL, just make sure you're taught by a professional, not an enthusiast. IMHO some of the best instructors are fresh out of a frozen ATPL course. They've had SOPs drummed into them, whereas enthusiasts may have some dubious practices which may work for VFR PPL, but if you transfer them to bigger things may not work.
As far back as my memory serves, companies employing modular newbies have always required 500 - 1000 hours. Whereas integrated guys can get a job straight away. Like it or lump it, this is the reality. Don't expect to get a job straight away (except as a FI, which will teach you LOADS and be incredibly rewarding) Remember to factor this into your calculations.
Having instructed for Cabair, I'm convinced that their schools are excellent. However they do charge a premium for the branding. Is it worth it? Maybe so for the more advanced stuff, but at PPL level I'm not convinced.
All the best with making your decision. IMHO the biggest decision is modular Vs integrated. After that it's a question of which school is best for you (where will you be happiest and where will be most conducive to learning)