Best 12V motor for variable speed on L294D

Projects General Guidance
1

So I am working on a fan that varies it's speed based on temperature or humidity. I bought some really cheap 12v motors ($1.00) at my local hobby store. They run fine for a day or 2 and then burn out and don't want to turn with anything lower than analogWrite(pin, 255).

My LBM does have better motors, for RC cars and what not, but I am looking for something maybe a bit smaller and not "as" pricey.

Any suggestions on a motor in the $10 to $15 range that would have good, long life a various speed from the L294D?

2

Some forensic research could be done with the defective motors, to find out the reason for their disease. What's their current when they run free from 12V?

If the motors burn out, is it due to lack of cooling (air ventilation), load, voltage or limited duty cycle, misaligned axle?

A circuit diagram would be interesting, and motor and power supply ratings. Is the L294 still okay?

There is nothing like a "best" motor, no recommendation possible without further information about your project and requirements.