I purchased the moto g in the year 2014 . trust me at that time this was one of the best mobile phones available in the market. I am still using it and I am quite happy with the performance. I would suggest you to buy the 16gb variant.
The software is more or less like the nexus devices and Google has done a great job by providing stable lollipop os for this product. They are also planning to extend marshmallow support for the device.