I’m wondering if i should have a faster but weaker arm tower, or a strong but slow arm tower.
The stronger gear ratio can pick up around 7-8 stars max, the faster one can probably pick up around 4.
Rarely would you ever have to pick up 5+ stars in a match, so my suggestion would be the faster arm, unless you also want to hang
Can I know what these gearings you are trying? You should be able to strike a good balance between them, and if you can’t maybe there are other aspects of the robot you should be changing.
Currently we have a 12:84 or 1:7 ratio powered by 6 torque motors. We’re thinking of changing to a 36:84 that’s still powered by 6 torque motors.
How about a 1:7 (12:84) with high speed motor gearing? Or with turbo motor gearing? Or 1:5 (12:600) with high torque? You have a lot of options here. 
Would the high speed motors be way to weak? I’m thinking that rubber bands should be able to help
If you’re not planning on hanging, you might as well use some rubber bands. 1:7 with a high speed gear ratio should be plenty strong enough if 3:7 is okay. High speed is 1.6:1 and turbo is 2.4:1.
high speed internals have a gear ratio of 1.6:1 and turbo have 2.4:1. Most teams have an overall gear ratio that lands somewhere between 3:1 and 5:1, so you can do the math to figure out what type of external gear ratio and internal ratio combination would work best for you and land somewhere in that range.
My team is currently running 6 high speed motors at 1:7. With rubber bands it can lift up to 8 stars or two cubes. It is also super quick. I would recommend having a high gear ratio as you can just pile on rubber bands to bring it up to the speed of a lower gear ratio without loosing the star capacity.
We found a 1:5 external ratio with 6 torque motors as well as some elastics (but just enough so that they help us lift stars and cubes but can still hang) was very effective for our arm on our reverse claw bot. May I ask what people have used for their claw gearings? We want it to be quick but not struggle when gripping up to 5-6 stars.
I would experiment with a 12:60 or a 12:84 with different internals to figure out optimal gear ratio for your robot. Do some research and you will find that a fast lift can lift 8 or more stars. If you limit friction you will be surprized on what a 6 motor lift can do on a small gear ratio.
My team uses two torque motors geared 1:7. We can pick up to eight stars but only in a certain position. 5 is about the average. I personally would want to gear it even higher but my team members don’t want to.