I'm assuming that you would be doing a one way truck rental (not bringing the vehicle back)?
When looking at transporting items as opposed to passengers, looking at a moving van rental vs a minivan rental wouldn't really apply. The seats in a minivan rented from a regular car rental company cannot be removed... you're really better of looking at a moving truck rental.
With UHaul, the rates included up to 8 days and 2200 miles free.
Because rates can change from minute to minute, based on availibility, it's impossible for me to give you accurate pricing information. But I can tell you than when I checked examples of pricing from these two companies, the Budget Truck rental rate was the cheaper of the two, plus you get unlimited mileage.
I'm not sure if a moving van rental(vs minivan rental) would be any cheaper for you, as I don't know what you were quoted for the minivans or SUV's, but hope this helps! Please let me know if you have any more questions!
Pages from this site, relating to this topic:
Moving Truck Rentals