Crystal Tower is complete and utter garbage.

[C-croft]

A friend told me CT is before Coil, That the gear that drops in ct helps players gear up to do coil am I wrong?

It is true. But keep in mind that the 'barrier' for entry into coil is full DL. You don't actually need full DL, but since DL can be purchased with philo tomes, it is expected that you work to obtain the full DL for many pug groups. Not always but a common requirement. With that said, being on a 1 week lockout for coil, 450 myth a week, and 1 week lockout for CT, you are almost better using CT to gear a second job that you wish to gear for later coil runs. Ultimately it is up to you. In the end, just have fun and enjoy the game.