4pcs TT Motor Dual DC 3-6V Gearbox Motor 200RPM Ratio 1:48 Shaft Motor with 2.54mm Wire for Arduino DIY Smart Car Robot

These are great low cost gearmotors for general applications.

Fun little project servos to use with my kids and teach them robotics/electronics It's fun to tinker with these work just fine for that. Probably wouldn't throw together in something I intend to use long term

I actually keep a dozen or so of these types of motors on my workbench for toy robot projects. They are easy to attach using zip types, hot glue or, if you're lucky, the bolt holes. These are obviously toy grade motors and are not very efficient, but they are inexpensive and get the job done. I control them using Arduino connected to an H bridge and have had no issues.

I’m in the process of working on some projects that need some motors in them, and these looked promising. The four motors are nice in that they have an axis that goes through the body, meaning you can connect your parts on either side - or both, and run them at the same time. The size of the motor and gearbox setup is small, meaning I can fit them into smaller builds easily while keeping power. The cables are a decent length that lets me connect to other connectors, including breadboards for either testing or operating. I’m happy with them!

seem to be good but had to return as the gear ratio did not work for my purposes

These are the same motors that come on a lot of low cost arduino (and likely other) vehicles and robots. The look like they were hacked together with spare parts, zip ties and such. But, they work. They are standard DC motors, which means, no positional capability. They're not the best option by far, but they're what I expected them to be.