In terms of outright speed, yes, TGV is the world's fastest on a max speed record and in-service average journey speed basis. However I would guess that an N700 or similar would have greater acceleration, especially from a stand due to the extra number of powered axles. I think a TGV-R has the highest power-weight ratio of any train but still only has 8 motored axles and would suffer more under traction compared to a typical shinkansen which has much smaller motors but something crazy like 32 of them per set.
Where the crossover point would be is hard to say but if you could arrange a side-by-side race, I would say the speed of a TGV-R would increase beyond the shinkansen probably in the 200-240km/h range by which time they would have covered quiye some distance and (again, a rough but educated guess) it would be many more miles before the TGV passed the shinkansen. So in other words for a journey of 20-30 miles, I don't see anything beating the likes of an N700. For a non stop journey of over 100miles, the records show a TGV is what you want.