Could you explain why ? The tack motor has adjustability and has really good reviews, i have not heard to much about the FCC motor but i have seen videos and it does look like it works very well.
i would go with a fcc motor. There gen1 motors were very good motors and very reliable. The tac motor is a very good motor as well but with sending it to tac you will have to wait at least a month and a half up to 3 months to get back as he gets very backed up. It will also cost you with shipping if you live in the states around 140+ once you convert from dollar to the euro then shipping. thats to fix your motor where as you can have a brand new fcc motor that is lipo ready just as good for 200 new out the box. and then sell your motor thats broken for 25 to 35 bucks and recoup some of that money or hold on to it till you have the money to get yours fixed by tac or hsa.
Systema motors are good but they fail just like the ctw motor spend the extra 70 and get a FCC motor trust me you won't be happy when your Systema motor goes down and you have 2 motors that don't work and need to be fixed. Go with the FCC motor that is rewound and upgraded so the problems that cause motor failure on the stock ptw and ctw motors is on existent.