Torque and speed are all over the map when it comes to DC motor drives. I have a pair of DC motors that came off a computer tape drive. These were used as servo motors to spin the reels very fast but stop on a dime when the desired area of the tape was found. I was going to use them with a brand-new 48 V DC lead-acid battery to build an electric go-cart, but my kids all grew up and left home before I could find my "round tuit".
If you are using gears with your DC motor, don't expect both speed and high-torque or even accuracy. Special servo motors I have used in the past had special zero-back-lash, split, spring-loaded, gears. They were very fast and very accurate because they computed ballistic coefficients for aiming a large cannon, mounted on hydraulically actuated gimbals, that fired while in flight. But each servo assembly probably cost the tax payers upwards of $50,000 dollars in 1960s money. You pays for accuracy, repeat-ability, torque, and speed. I like stepper motors, and many I have used incorporate planetary gear reductions, but adding a shaft position encoder can be very tricky and you have to watch out for mechanical resonances excited by the stepper impulses. In many ways, a DC servo motor is a better choice, but only experience will point you in the right direction. Well, it doesn't have to be your personal experience. Learn from others and tell us what you want to DO. Specs (numbers) are a big help.