I haven't heard that JBL model, but I had Alon II's and KEF 105.4's.
The Alon is a more audiophile type speaker, and has a higher ceiling sonically if you have the right gear, room, and placement. I couldn't get my Alon II's to reach their potential in my room - couldn't get far enough from the back wall and I have too many reflective surfaces.
The KEF will be more forgiving and sound a bit more vintage (warmer), but still sounds quite good. Would also benefit from a crossover recap, etc.
If you can buy the Alons for a price that would enable you to try them out and resell if they don't perform well in your environment, I'd definitely give it a try - they could be the last speaker you own.