If it's your first time in a NW parlour, then Sandys and La Maison are sure to be favourites as others have posted. Loads of other choices though if a parlour is not your main criteria as TCM mentioned.
Sandys in Prestwich is possibly better than Northenden for room space and choice, but both are really top notch and run like clockwork normally. Some quite fantastic girls at Sandys. La Maison is the same, with some really good rooms too, but a little more laid back once you're there which is great. They also have their own selection of fantastic girls!
Look at their own websites, you will not go wrong at either, but for a first time parlour visit, La Maison just wins it I'd say as it can get very, very busy at Sandys sometimes, which might be a lot to take in on your first visit there.