I love the sound of a cat's purr too - gentle or loud, I dont care when it's generated from a place of contentment.
Moray's purr is loud, but Tinks has a quiet purr - a shy purr, which makes it even more delightful when you can coax one out of him.
Ross used to have a mega purr - he would purr on the in breath and the out breath, and it always made me smile.