I haven't fully read all the other replies on this topic, but I will tell you what I think.
I personally use the Contax line of lenses.. Carl Zeisses are amazing lenses to work with. The 21 and 28 Biogon are unbelievable sharp, and currently going for at good prices.. new and 2nd hand. Many G series users are desperate to get rid of their system because they are worried that they won't have anywhere to have their camera serviced, but don't worry... the G2 is still servicable for the next 10 years.
I would usually choose a system buy its glass. And trust me, you won't go wrong with the G series.
The AF of the G2 will take a little while to get used to, but once you've gotten the hang of it, the camera is really a charm. Some find the focusing noise a little loud, but I think its slightly quieter than the R3a.
You won't be disappointed with the G2