Tow flat or with dolly?

As the others have stated, there is no universal "best way". It's a function of personal circumstances. Having done both, I can say it's less expensive to use a dolly but a pain in the behind to move it around and worry about storing it. It took a little longer to hook up the safety straps and chains and was a little messy if it was raining. 4-down is a breeze but cost me $$$'s to purchase a towable car and will be expensive if I replace the car to purchase and install a new base plate, etc. I've included a break down based on my costs in 2012 showing the difference between the dolly and 4-down items that may be of some assistance. I tried to format tabs but the final product doesn't reflect the 3 columns, sorry.

Tow Dolly v. Four Down Towing Comparison

DOLLY 4-DOWN
Need new vehicle n/a yes
Dolly w/ surge brakes $1250.00 n/a
Tow Bar n/a $600.00
Tow Bar Install n/a $0.00
Brake system n/a $1250.00 portable system (less if installed)
Brake system install n/a $0.00 total L&M for installed system +/-$1300
Base Plate n/a $355.00
Base Plate install n/a $450.00
Receiver n/a n/a add $100 if receiver adapter is req'd
Auxiliary lights $20.00 n/a
Wiring labor & materials n/a $315.00 diodes
Safety cable included $100.00
7 -> 6 pin cable Included $100.00
TOTAL $1,270.00 $3,170.00