I have had both. If there are multiple Bamboo shrimp in a tank, they will tend to spend 60-70% as part of the group, the rest of the time they go off to either hide, or scrounge around the tank.
I personally prefer multiples. With a tank setup for filter feeders, they can be very hypnotic as they do their 'fan dance'.
Either way, they seem happiest in tanks with a powerhead to create a strong current. If you have a HOB filter, you may want to take precautions to keep them/it from climbing into the filter. If one climbs in and dies, and you don't catch it quickly, it could foul the tank water. Plus, I know know many who keep other scavengers in their HOB filters to eat the corpses. I only have one tank that gets critters in the HOB filter. It's my snail only tank, and baby MTS get sucked in and crushed by the impeller.