I would recommend V-Cube (more expensive, but, much better)
Smoothness:
V-Cube: Amazingly smooth.
Professor Cube (Rubik's): Tight, and bad quality control
Durability:
V-Cube: Very Durable
Professor Cube (Rubik's): Prone to break
Popability (Rate of cube pieces flying out):
V-Cube: Very Low, Almost Zero
Professor Cube (Rubik's): Higher
Sticker quality:
V-Cube: Very good, almost like vinyl stickers
Professor Cube (Rubik's): Very bad quality
Breaking in:
V-Cube: No breaking in required for 100% performance
Professor Cube (Rubik's): Need a long long time to break in
Therefore, adding up some of these points, we can conclude that V-Cube is the best choice. If you do not believe it buy one and see for yourself.
And for the 3x3 part, I'm sorry, there are no 3x3 V-Cubes, as they have not mass produced it yet, but it might be in the near future. Rubik's 3x3 is the only one. But, if you compare it with the 3x3 DIY cubes sold online, the DIY cubes are much,. much better.