Suggestions for water purifier

Hi All,

Currently I am not using any purifier, using direct tap water with cloth filer only from last 15 years, no issues.
But now as I need to move to other location I have to buy a purifier.
Can someone suggest me a good water purifier with minimum maintenance cost. I dont have any specific requirement.
The only thing I worried about is Thyroid, one doctor suggested me not to use any electrical water purifier as it removes all required minerals also and can cause for thyroid (one of my family member has thyroid), instead he suggested to use gravity purifier.

So Can someone guide me for good purifier, electrical, gravity anything with your experience?