It all depends on your budget, time on the track, desire to be the best and your driving skill.

I recently converted all my cars; sedan, USGT, VTA and F1, driving on black CRC, to the Tekin T-120. Very expensive as servos go, but barring a failure, I plan to grow into them skill-wise and experience gained and keep them for years.

Buy a good quality used one if you are new. If you are experienced, then you probably already have a brand preference.