The list would be long, if "better than" is the only criteria.
Pretty much any union CAN represent. Doesn't have to be a transportation related union. If I remember correctly, Uber drivers signed cards for representation by a Machinist's union.
In my opinion, FedEx pilots union would be BEST. But they declined our request back in the day, being the elitist group that they are. If they had the good sense to think It though, imagine the leverage Drivers AND Pilots combined could have.
Feel free to start a thread on the topic of which union(s) could be the best choice. I'll play.