I'd start with reentrant rather than low G for a couple of reasons - first, as Sukie mentioned there are a lot more resources available for it, but also because a lot of strumming/beginner material doesn't sound right on low G unless one has the knowledge to look for alternate chord inversions. With low G, that 4th string is always going to produce the dominant note, and if it's not the root of the chord it may sound somehow "wrong." It certainly did to me when I was starting out! This especially applies if one is playing low G but is playing the same material in a group of others who are playing reentrant.