Any brand new boat will be a good boat... but, the Lund is more expensive because it's worth it.
Lunds are built stronger and sturdier and their resale value is one of, if not the highest of the aluminum boat makers.
I'm not trying to take anything away from the G3s but I visited their website recently and took the virtual tour of how the G3s are made and I'm not overly impressed with their below deck framing/construction. They use longitudinal stringers instead of elevated ribs, this leaves fewer options for floatation foam installation and amounts. It also leaves something to be desired for below deck drainage.
If I was going to buy brand new and finance the boat I would definitely go for the Lund instead of the G3.