I have both of these cameras. They are simply too different to give advice on which you should get. It's just too personal a choice. There is a lot written here and elsewhere on the web to give a sense of the standard pluses and minuses, but you should do your best to handle each, look through the VFs and decide which feels better. I love the G lenses, they are the sharpest, most contrasty lenses I've ever used, especially the 28 and 45. However, the reason I got into Leica mount system in addition was to tap into the much wider range of lenses available both in price (in price ranges, from $20 Jupiter-8 to multi-thousand ASPH 35/2) and in lens characteristics and personality (50 year old LTM lenses w/adapters, Leica m-mounts new and old, classic Canon lenses, newer VC lenses, etc.) which allows me more creative freedom from the limited range of G lenses and their bitting sharpness/contrast. That said I'm selling my R3A only because I bought an MP as AE does not fit my style for my uses of the Leica and Leica-mount lenses. I prefer a "match-needle" type of metering for that. But I am not selling the R3A because of dissatisfaction with its performance or use.
Email if you are interested in my R3A and want to see photos of it. Its pristine, in box, with original receipt, and only 6 months old. Maybe a dozen rolls have been though it. I'm asking $500 + shipping.