Although the combination of the Fitting Room and Morph Brush can give a superior result, there is a steep learning curve to get the outfit to fit just right.  If you're looking for something straight out of the box with minimal adjustment and fuss then my choices would be Crossdresser and the Fitting Room.  Morph brush for cosmetic correction.  Don't forget Morphing Clothes, if still available, but that program seems to have been replaced with the copy morphs in Poser.