Direct replacement to the very expensive OEM brand, but quality suffers
The OEM replacements are insanely expensive, but I get about 6 months out of them before my toothbrush tells me to replace the head.  With these, the clean is just as effective and the bristles are soft, but I find myself replacing them almost every month.  I give them 4 stars because they are a compromise between money and quality.
Rating: 4 stars