The Towel Matters Just As Much As The Rack
Different towel fabrics and constructions behave very differently once they are hanging on a heated rack. Some warm up quickly. Some dry more thoroughly. Some feel thick and luxurious but hold moisture longer than expected.
That is why the best towel is not always the plushest or the most expensive one. It is often the one that fits the way the rack will actually be used.
Lighter Towels
Usually warm and dry faster.
Denser Towels
Often feel richer, but can need more time and more bar space.
Weave Matters
Flat or open weaves often release moisture faster than thick terry.
Two households can have very different experiences with the same towel warmer simply because the towels themselves behave differently.
The Main Fabric Factors
Weight
Lighter towels usually dry faster and warm up more quickly.
Pile Height
Plush looped towels often hold more moisture and need more drying time.
Density
Dense luxury towels can feel excellent, but they often need more heated surface area to dry well.
Size
Bath sheets need more bar space than standard bath towels, no matter what the fabric is.

How Common Towels Usually Behave
Cotton
The broad middle ground. Lighter cottons usually dry well, while thick plush cottons may need more time.
Egyptian / Turkish / Pima
These can feel richer and more absorbent, but the denser styles often hold moisture longer as well.
Waffle, Linen, And Lighter Weaves
Often release moisture faster and can be very satisfying on a heated rack, especially where quick drying matters.
Microfiber And Synthetics
These can dry quickly, but the feel is different and they do not give the same bath-towel experience most people want in a primary bathroom.