These subs are so different that they aren't often compared. The VTF15h is a very large sub that has lots of output. The F12G is a much smaller sub that places much more emphasis on low distortion than output. The VTF15h will likely have many times the output capability than the F12G, but if you don't listen to stuff loud, the F12G might make more sense for you. I would say if your highest priority is low distortion and accuracy, go for the F12G, but if you want some dynamic range, go for the VTF15h. However, it isn't like the VTF15h is going to sound sloppy, it will be very good for accuracy and low distortion, but I just wouldn't expect it to match the F12 in that respect.