I can only weigh in on the two types I have used. The first are the 6mm paper-tube filters branded Medico or Dr. Grabow. I do not recommend them. They restrict the draw to a degree that I do not like, and for me, they do mute the flavor of any tobacco to a significant degree. The first smoke tastes papery from the new filter, and by about the third smoke they taste disgusting from all the soured crud trapped in them. They do absorb much moisture from the smoke.
The second are the Savinelli balsa absorbers or homemade ones I cut from balsa stock. They do not impede the draw to a perceptible degree, and I don't notice any muting of flavors. You will get more mileage out of one before it gets sour and nasty. They also absorb much moisture from the smoke, and I strongly recommend them.
That being said, I prefer to avoid filters altogether by smoking tobaccos that produce less moisture in briars, and smoking tobaccos that are known to produce more moisture in cobs, which are naturally more absorbent than briars. I don't use filters or absorbers in cobs at all.