I'll refer to a particular model of the Kawai digital pianos.
I had nearly the same dilemma a while back... I had been playing piano for 3 years, but strangely practised only on a keyboard. I rarely had access to a piano in school, and soon realised that I would need a proper keyboard (not an acoustic piano, because portability is a major factor for me) and also needed fully graded hammer action keys.
My answer will only apply to you if you're looking for something under $1000, but the Kawai ES100 digital piano is SPECTACULAR. It is one of the most cost-effective pianos available out there, is portable, very sleek and can easily be accommodated in a small space, and has great hammer action and sound.
They took individual samples from each of the keys, unlike other companies which simply sample an octave and adjust it across the board. Even if sound is not a factor for you, you should go for this one because it comes as close as possible to the real thing at this price, and has been cited by many to be at par with several more expensive pianos by other companies...