Yassers is now one of the most miserable places to visit, I usually only go with someone else who wants to see it. His brother and the other fella who works there are miserable and try to rip you off.
Mahmoud is generally consistant. If you want something made to measure for a reasonable price then i strongly recommend Oriental Moon
Oriental Moon Atelier - Leading Designers in Raqs Sharqi Couture they will also collect you from your hotel which is fantastic, an all round great service.
Taxis vary depending on which hotel you are staying at. The best thing is to pay what you think is right and give it to him as you get out. If he starts a fight ignore him, the law is always on the side of the tourist in Egypt.