I prefer the Halti. Much softer material. A lot more comfortable for a sensitive dog.

When i was fitting them for Koli she was going spastic on on the Gentle Leader. I tried on a Halti and she did fine.

Also, a determined dog can easily slip out of a Gentle Leader.

Make sure you fit them right. If you pull up and the dog can struggle out of it, it's too loose. (Idiots at both stores didn't have a clue though they said it was fitted right. I had to have a professional trainer re-adjust it for me and show me how to properly use it. Even reading the inserted book didn't help for proper fitting... but it does have a LOT of great advice.)