I'm a big fan of Westbourne Grove and part of Bayswater directly south of Royal Oak tube station. I lived for a while on the quieter end of Gloucester Terrace and loved it. Great amenities, restaurants etc. Bayswater has loads of studio flats. And you couldn't ask for a better location, esp if she has to walk to Pads.
If it were me and I had the money, I'd either be focusing my efforts on Marylebone, west towards Notting Hill Gate and maybe Little Venice (Warwick Ave tube) and around the Regents Canal. How awesome would that be to walk along the canal every day to work? And slightly further afield, around Primrose Hill - but that'd be a heck of a walk.
Honestly, when it comes to Paddington, there aren't many areas I'd say to stay away from, except for maybe right next to the station - far too busy for my tastes. I've always found Edgeware Road to be a bit on the dodgy side, however I have girlfriend who lives just off it and loves it, so to each their own.