Aikido
A Mixed MA called Carisma (Kickboxing, Jiu jitsu, Muay Thai, Aikido)
Jiu Jitsu
Karate
Combat Sombo & Submission
Kali
Savate Kickboxing
French Cane
Empty Hand/Close Quarters (whatever that's supposed to mean)
Doce Pares Eskrima
Shotokan Karate
Muay Thai
Wing Tsun
Ninjitsu
You have some good options there.
Were I you, I'd take the FMA (Doce Pares, Kali) and French Cane for weapons work. The FMA stuff will teach knife work, which is always good. I don't know anything about the French Cane, but I've heard some good things.
I'd do the Sombo for ground. I'd suggest the jujitsu, too, but I don't know if its Brazilian or not...if so, it'd also be good for ground work.
In picking one similar system over another, I'd pick the instructor that I felt was the best for me. If you have a personality clash with the teacher, it doesn't really matter how good the system is.
The Shotokan and karate are great ways to get some more insights into TKD.
The Wing Tsun would be an interesting blend with TKD for close in trapping and punching work. The Muay Thai has great kicks, knees, elbows that will augment your TKD. The clinch work done in Muay Thai is awesome...and sets up a lot of throws. Savate's kicking would compliment the stuff you have from TKD.
I tell my TKD students that they have to take a certain number of hours of FMA and grappling if they want to get a black belt in TKD. This way they won't be totally clueless when it comes to weapon work and ground fighting. Along with that, alot of them take Jun Fan, Muay Thai, kung fu, T'ai Chi...its all good stuff.
You have a lot of choices. That's a good problem to have.
Regards,
Steve