Personally I'd recommend learning 2 over 3 for the simple reason that one of pythons big selling points, for me, are some really great libraries and tools, which you won't be able to use if you use python3. That being said I'd focus on python 2.7, using the the back ported python 3 features and avoiding all the depreciated features. That way if and when you do switch to python 3 the shock will be lessened.