I don't know which is smaller, but if size isn't an issue for you, and it's going to be your only pump, then I think the bigger size would be better.
That said, a regular, full-sized pump at home can be really nice to have, and, even if you get a cheap one, you may find it works better than the portable pump.
I was using a cheap (around $10, I think) foot pump for my in-house pump until it broke, but after many years of use, I didn't mind. However I did then go out and buy the Topeak Joe Blow pump for the house, and I really like that one, too. But I think even my cheap foot pump would have been preferable to the Road Morph. Every portable pump I've tried goes for portability first and utility second. Road Morph is the most usable of the lot (that I've tried), but it's still not as good as a "real" pump. It's just much, much easier to carry on your bike.