Parlours are a good place to start, perceived to be safer, you get a choice of girls (but not types) and you can plan your punt better. However, you definitely need to get break out of the parlour pattern, I didn't realise early on that Indy's can be offer a lot more. They are just as safe (100+ punt and no safety issues) , there are so many different shapes/sizes/nationalities out there to try who can offer a dam good service. My gut feel is that, you will never find a reg in a parlour, I might be wrong on that but as you say the conveyor belt process means you can visit the parlour every week and they just never get that close.
My preference is for a GFE experience with a couple of regs interspersed with a random selection of girls that just take your fancy/wallet.