You will probably find lots of varying opinions here also.
I don't think that towing will affect tread choice.
If you expect to driving off road in sand then an all season tire is better than an on/off road or all terrain tire. The more aggressive the tread, the greater the tendency of the tire to dig in when in sand.
If you expect to be in mud or soft ground, then a more aggressive tread is desirable.
I rarely had problems in the sand with all season tires.
In addition, all season tires will be much better suited for the road in that they will be quieter, and probably have longer tread life.