Just popped into Halfords for something else and they had a Carrera eBike with a hub motor that said it had a torque sensor, for the bargain price of a grand. Looked ok.
Now, my Mum's eBike has a hub motor and I thought it was normal they didn't have torque sensors. It's a bit weird because as soon as you move off it gives you the full amount of whatever power you've set it to. But presumably with a torque sensing hub it would be a bit better. I'm sure a BB motor would be better but a grand is pretty cheap for an eBike.
It's this one, Carrera impel im-2.1
the issue with a torque sensor in the rear hub ( and I have ridden one) is its sensitivity alters according to the gear you are in ie in a high gear you need to push harder on the pedals to get the motor to kick in than in low gears). Better than cadence sensing but not as good as a BB torque sensor
STW's "skim resources" breaks links for me but is it the same Suntour system as the Carrera MTB's use? If so then it's torque sensing in the chainring. My OH's got one and it's actually smoother than my Parents Bosch bikes. The only downside is it's weight and weight distribution.