I've got a couple of Nova'a, a Nova+ and Primus Omnifuel. When burning liquid fuel like parafinn/coleman fuel there is nothing really between them in terms of burn time. The Nova is a little more frugal on paraffin than the Primus. You don't need to change the jet between different fuels with the Nova's, you do with the Primus, but, you can use a gas cartridge (standard screw type) with the Primus.
If you don't want the option of burning gas, then just flip a coin, they are both very good stoves
I don't burn unleaded petrol, it really does give off fumes you don't want to inhale, and the additives will clog jets quicker than cleaner fuel. I burn paraffin or automotive panel wipe I get from a local car spares centre (way cheaper than Coleman)
Good luck with your choice, you have the pick of what I believe as a stove collector, to be just about the two best expedition stoves on the market