Preference... The part of BIAB I don't like is that you constantly adjust heat, (utilities are evil!) I do a modified version. I use a grain bag in a Gotte cooler. Makes sparging and filtering an absolute breeze.
As far as cleaning the bag? Just fill a bucket with clean water and agitate to get the sugars off. then hang the bag to dry. When dry, turn it inside out and just shake the grain husks off. Bags don't need to be overly sanitized, as they go into preboil step anyway.