I experienced no curl loosening with Jamila but it makes my hair so dry!
I've been using henna for about a year now so I'm not expert but I prefer henna from India - Rajasthani region - Red Raj and Rajasthani Twilight. I've tried Nupur but mixed with Jamila so I can't really judge it. It has amla in the mix so that may help people get darker tones.
I would like to try the Moroccan & Yemeni henna soon from Hennasooq! But with the crazy political situation in the Middle East according to the news, I'm not sure if it will be available again anytime soon. I also read that its not good to freeze Moroccan henna.
It seems like my hair is softer and looks thicker after using it. When I first used Twilight, it seems as if my hair itched but I'm not sure if it was because I didn't rinse properly. After the dryness I experienced from Jamila, I started to add honey to my mix and its like heaven! Easy rinse and softer hair!