Most home dehumidifiers fall into two types. Compressor units and desiccant units. Each has strengths and weaknesses.
Compressor dehumidifiers
These are the most common. They are efficient in warmer rooms and tend to have the lowest running costs in typical heated homes.
Desiccant dehumidifiers
Desiccant units use a different method that keeps working even when the room is cooler. They are useful in garages, conservatories and unheated spaces.
Which should you choose
For most heated homes a modern compressor model is the best starting point. If your main problem is a cold room or outbuilding then a desiccant unit usually performs better.