IF You have a crazy horse then with a lunge line may be a bit safer just so you can control them a bit more. At the same time though it may be beneficial to free lunge your crazy horse to let them run around And let their energy out.
My horse is very lazy and most times doesn’t do anything if I free lunge her. Sometimes though I will take off the lunge line after a few minutes of lunging and if she’s doesnt realize then she continues to lunge in a circle without a line.
Lunging with a line. I see it as slightly safer and beneficial, the horse can’t run around like crazy quite as easily and you don’t either need a enclosed space or really high fences for it. I never really freelunge anymore, partly because my horses don’t quite get it, one just stands there and the other one is already crazy enough on a line, but mostly because I had a scare when my pony jumped the fence and ran to the woods😂