During my long RV life, I have done both.
I towed several different Jeeps and a Dodge Ram 1500 with towbars. It worked. My Jeep towbar was a Reese fixed arm adjustable width unit, $65 at Walmart years ago when I bought it. I tried backing up once, and it didn't work. Since then, anytime I'm in a position where the choice is try to back up or disconnect the towed, I disconnect. Never again will I try backing a towed vehicle.
I towed our PT Cruiser on a Kar Kaddy dolly, from MT to GA and back. Again, no problems. During that entire trip, we only had a back-in site once, where I had to disconnect the car and dolly.
IMO, there is no "BEST WAY", there is only personal preference. It all comes down to: "What do YOU want to do?"