If I had a dollar for every time a customer asked me which shaving soap is the best shaving soap available, I would be a rich man. Unfortunately, this is not a question that can be answered with a pithy definitive answer. After all, there are a lot of really good shaving soaps on the market and, there are a million variables that come into play including water hardness, skin type and what kind of razor you are using (straight razor, double edge razor, artist club razor, Gem style razor, cartridge razor or something different).
So, the best that I can do is to give a few recommendations with the caveat that your mileage may indeed vary. Here are my top 5:
1. Czech and Speake. -The Czech and Speake soaps are tallow based soaps made by Valobra (also great soaps). It comes in two scents -No. 88 which is a complex dirty rose scent and Oxford and Cambridge which is a lavender/mint blend. These soaps are on the pricey side ($33.99 for a 90g refill puck) but, they last a very long time which makes the actual cost per shave very reasonable. These soaps lather easily, the lather produced is creamy, slick and protective and, they have great post shave skin care qualities.
2. Le Pere Lucien (Tallow Formula): Le Pere Lucien comes in two formulas, a new tallow based formula and their traditional vegetable based formula. Both formulas are great but, the tallow based formula really shines. The Lather is extremely rich and creamy and the OUD-Santal scent is extremely well done. Although this soap is currently out of stock, there is a small batch on the way as well as plans to make it a regular offering. The soap comes in a huge 200g stainless steel tin and will last a very long time.
3. Asylum Shave Works (Tallow): The Asylum Shave soaps offer excellent performance at an excellent price. These tallow based soaps utilize the soap base from WSP's Formula T soaps but, they have more complex scents. They range in price from $14.99 for the simplest scents to $18.99 for the most complex scents. The Royal Fougere is a traditional English Fern type scent that punches way beyond its price point.
4. Klar Shaving Soap: My first three soaps listed are all tallow based soaps. Generally speaking, I find tallow based soaps to have a creamier and richer lather and, I find that tallow soaps are less likely to dry out my skin. That said, Klar Seifen shaving soaps are vegetable based and, they are excellent.
5. La Savonniere du Moulin Donkey Milk Shaving Soap: La Savonniere du Moulin shaving soap is a vegetable based shaving soap with added donkey milk. This soap lathers very easily. Although the lather is not quite as creamy as a top tier tallow based soap, it is extremely slick and, the post shave feel is outstanding (purportedly due to the Donkey Milk). Everyone should have a puck of this soap in their soap collection.
Honorable Mention: As I had mentioned previously, there are a lot of top tier soaps on the market these days. The Le Savon des Volcans shave soap stick deserves mention. This soap is an extremely hard vegetable based shave stick that produces ridiculously slick lather. This soap is a favorite for those that use a straight razor. Although the scent is a simple and straight forward peppermint, it is enjoyable.
While it is impossible to say which soap would be best for you, this list is a good place to start.