There are numerous discussion on this topic. See these threads below. While Adobe RGB (or aRGB) gives you bigger colour space, practical situation calls for sRGB mainly because in general, most colour printers including those in photo developing shops able to manage sRGB.
i shoot raw, and mostly convert to sRGB.. coz it's easier to share photos and print them. Like others have said, most photo developing shops read sRGB, and most photo viewers support sRGB. So if u are looking to share photos, it's better to use sRGB or ur friends might be looking at wierd colours.
I always keep the raw or tiff files just in case I want aRGB or even prophoto.. But that's rare though, unless I go to a shop that can process such colour spaces, or I buy a new printer.