I agree with Jeff Howell that a "torch-on" felt roof is a good option. Allow for around £50 per square metre for that.
But, recently, I've used EPDM rubber for the first time. It's a great product with a good long life ahead of it.
Nothing wrong with the fibreglass system though. I'm afraid it's down to your choice, Nisar. As with all these things, it really must be done properly by someone who knows what they're doing.
I do like the rubber though ;o)