Obviously each person tows the way they prefer, for a wide variety of reasons. There is no "best" way for everyone, each person tows the way that's "best" for them.
Here is my opinion. I prefer using a dolly because:
I can tow most any vehicle, not limited to the one with the equipment installed.
I didn't have to install a braking system in my toad and MH.
I didn't have to install a tail light system on my toad. (It's on the trailer.)
I didn't have to install a transmission pump on my toad. (Not all vehicles require this, but both of mine did.)
I can trade my toad in anytime and not have to pay to have all the equipment installed on the new car.
My dolly was less than half the price of installing all of that equipment.
When parked, my dolly will slide up under the back of the MH and only stick out 24".
I can load up my car onto the dolly with little time and effort.
Did I mention that my dolly cost way less than towing 4 down?
These are some of the reasons that I prefer a dolly, others have good reasons they prefer 4 down. It's all a matter of personal preference.
Good luck with whatever you choose to do.