Sigma 19mm or 30mm for general use?

I'm not sure which to buy. Tried them both with excellent results. I want a compact lens for the NEX5 for quick shots in the street, hiking, holidays, etc. The 19mm would give me the greatest angle, and I could crop to 30mm or more in PS if needed, or is this false logic? Which is the most useful walkabout focal length? Opinions would be welcome. Thanks.