Some devices struggle with NIMH batteries, which are only 1.2V
Alkaline batteries are 1.5V, are usually charged, ready to use and can be recharged many times.
Alkaline batteries must be recharged in a purpose built alkaline charger to ensure long battery life, do not use an NIMH charger, even if a well meaning person says it will work.
Alkaline batteries are not very popular due in part to past faulty manufacture, but current recent ones should give good service.
Remember, you need 8 alkaline batteries for 12V or 10 NIMH for 12V, so no cost advantage between the two types.