As @Gigahertz.t pointed out, optimal drive speed will mostly depend on your game strategy.
Then, as you develop your subsystems over the season, you will settle on the weight of your robot, which is both limiting factor in how fast you could accelerate (lighter robot could accelerate faster without requiring a lot of torque from the motors) and with how much force you could push opponents (heavier robots, obviously, convert their weight into more pushing force through the coefficient of friction of the wheels to the ground). You cannot have a lot of pushing force with light robot as wheels will lose traction, and you cannot accelerate and drive fast with heavy robot as you will just overheat your motors.
So, the combination of robot weight and drivetrain type will determine effective range of the acceptable gearing ratio (see this topic for more details). It’s an evolution process of building prototypes and evaluating their performance.