I suppose 'soap' is a good subject for these days of hand-washing obsession.
I've never really had particularly favourite soaps; they have either easily foamed or not foamed, and I preferred the former, regardless of its name, price, shape, scent, or consistency.
These days I only use Le Petit Marseillais liquid soaps, as they are the soapiest soap of all known soaps that the world has ever encountered. One has the feeling that they do the cleansing job exceptionally well. Hand washing becomes a pleasure.
The lemon scented bar of Le Petit Olivier soap was a recent purchase (Lady M's), and seems to be cashing-in on the popularity of the Petit Marseillais, but it's nowhere near as good. I'm not so keen on solid 'bars' of soap anyway.
I have no idea if these liquid soaps are available everywhere, but they are so very good.
I only have one anecdote relating to soap; I have a friend who lives nearby, who used to buy industrial multi-packs of Pears coal tar soap from the UK. She said they reminded her of freshly-scrubbed small boys, and she would use no other. She didn't elucidate about the small boys; which is probably a good thing.
I'll stick with the above.