I agree with Granny.
It is impossible for any training school to guarantee a student a job, without knowing them. However, It is logical
PR for a training school (that can offer employment to low hour pilots that have trained with them only) to advertise that in order to encourage students to sign with them. The basis of any advertising is to dangle the carrot as hard as you can isn't it?
In selecting a school I would concentrate on their reputation, how long they have been established, how busy they are (a busy restaurant is usually a good one), and the experience and personality of their instructors. You must meet them first and sus them out, their ego, patience, etc. In terms of their experience, don't just look at their total time and background, but also their instructional time and whether they are grade 1 or grade 2 instructors. And if they can also offer employment afterwards, then look at that as a bbq bonus.
You will carry your initial training throughout your career as a pilot to some degree. Training is planting a seed, and you want to grow a good tomato plant from that and not a dodgy one eh? I have done BFR's for experienced pilots who have done things in strange ways "coz that's how I was taught how to do it", and never really questioned or understood the method.
In short, I reckon you should pick a school for it's quality of training and staff, not just whether they MAY me able to give you a job afterwards.
If your a capable, keen and committed low hour pilot who isn't a complete gonzo, you'll get work, it's just a question of time and maybe a bit of luck. Your first job relies almost totally on your attitude anyway I reckon, and there's a whole lot of operators out there that aren't also training schools.