Finding a Yashica with a still functioning meter is at best, difficult. I dont trust the meters in them due to their age. I always use a hand held meter with my Yashicamat(non-metered version) or use sunny 16 rule.I have a metered porro-finder for my Mamiyas that is accurate, I trust it and always hit the proper exposure.
If I were to choose between the 124 and the G models, it would be the plain 124. The 124G has plastic innerds and is prone to early failure, while the 124 is all metal gearing, and better made. The G stands for gold, they used gold plating on the electrical contacts is all.