‘which’ is a publisher who review things. I do not have a subscription but know a place that does so one day i use it for six minutes to look at electric toothbrushes which dentist vet wants me to buy (my blog).
I write down the top two which look ok and later on google to find that those model numbers are from 2010 and so are mostly ebay products and secondhand. Both have different identities now with newer models in proper shops.
So still none the wiser.