I have two different ones:-
1. Ocean and Earth U-shape that I walk with. I ge4nerally use this one with my 14 footer. Have had for a number of years and does a good job. has an eyelet for putting a bike chain through for locking. Board is transported on its side and you hold the nose.
2. SUPWheels. fairly versatile. Board is deck down and you hold the nose with a hand. You can get a strap system that you loop over the seat of your pushy and use like a trailer.
Both are good but I like the O & E better.
ET.