Good advice, Karate Ueschi Ryu or any of the toughest in the traditional branch is what i would recommend any fighter, but only under the proviso you condition your whole body the old ways and spend hundreds of hours in the KATA's and techniques build up the bodies tolerance.
Same for Taekwondo do it if you love kicking and have already great kicking agility, mobility, strength and technique for guys coming of Muay Thai.
If you embrace not just what you learn in the session time but everything about the system and its roots and methods of training you will not only acquire the knowledge but the deep understanding to develop yourself and express your self in that art being the best you can be in it.
In the application of study there is the theory and the willing to learn and apply the original methods and purpose for the various techniques, thats the forgotten aspect to true Martial Arts............embracing it to its core depth!
Both are awesome systems in a great student and practitioner of the art!
Great video doc to watch -
https://www.youtube.com/results?search_query=uechi+ryu+karate+documentary+