MakeToys was my choice.
Here's something I point out to my friends who ask me why I chose MT versus TFC and the reason basically comes from TFC (Not in a good way)
To me, when you release a product and then subsequently, you release an "upgrade" kit for your own product, to me, it's like admitting that you messed up the release of the figure of some sort. I know some people won't agree to it and would think " It's cool you can get an upgrade kit for TFC combiner" This has happened with Hercules, Uranos and I would not be surprised at all if they do the same with Ares.
i'm not saying I have a hate on for TFC. I personally don't like the look of some of their designs. I do have their products like Photron which is pretty neat and their Iron Army which I regret getting in hindsight.
Go wih MT as I think thats a good choice. At least scale wise it will be good with their future release of Quatron
Good luck with your decision.