fista1: 4. DRM free digital version(for example here at gog.com),
I prefer games on CDs or DVDs. I will only buy a digital copy(and only via gog.com or Steam) of a game when it's the only way to get it or when it's much cheaper than in the store. But it has to be really a good game, otherwise I will wait while the game will become cheaper in retail shops(The Incredible Adventures of Van Helsing).
In general, I don't trust the digital distribution much. Yes, Valve stated that they can release a patch that will make their games playable without Steam, but what will happen if they go bancrupt and I haven't downloaded my games? From where will I be able to download them? This applies for the other digital stores as well.
I've still got a bit of an irrational attachment to hard copies of games as well, but this seems odd to me. If the digital version of the game is DRM-free, then simply purchase, DL, and burn to disc/store on HDD/USB stick and it's yours forever. Doesn't matter what happens to the store itself. I have all my GOG and Indie bundle games stored on my storage drive as well as backed up on an external.
For myself, the list would be similar except that number 4 would be number 2 for me and the others would move up in position.
(On a side note, even though I use Steam, I have no faith whatsoever that Valve will release a patch to make all their games playable without Steam if the company is going down the tubes. I think anyone that believes Valve will do this is fooling themselves).