I have never used anything other then CoachNet. Paid the premium for 9 years and never needed it. Then "BOOM", 90 miles from the closest diesel garage I was stranded. CoachNet sent a lowboy 90 miles to me, loaded me up and towed me 90 miles to a Freightliner garage where they made an immediate appointment for me. Two hours later and zero out of pocket towing I was back on the road again.
There may be good reasons to seek another service, but I would not consider saving hundreds of dollars for another towing service. Piece of mind is priceless when your stranded.