Shaving with a safety razor is very different than shaving with a cartridge razor. Does it require a special shaving cream? Do you even need shaving cream?
What is the best shaving cream for safety razor?
There really isn't such a thing as shaving cream made for a safety razor. A Safety razor will work just fine with just about any type of shaving cream, gel, soap, or oil.
All Shaving Cream, Shaving Soap, Shaving Gel, Shaving Oil, and any other type of shaving lubricant have 2 primary purposes. The first is to lubricate and protect your skin while shaving. The second is to moisturize your skin. Some products contain fragrances that provide a third benefit of making you smell nice.
Since you have or are thinking about switching to a Safety Razor here are some considerations when it comes to shaving cream.
Most commercial shaving cream comes in an aerosol can that has some nasty stuff in it. There are gasses that help produce the lather and alcohol which tends to dry out skin instead of moisturizing.
When most men switch from cartridge razors to safety razors they also convert from Shaving cream to Shaving soap. Shaving soap provides superior results however it requires a shave brush and some effort to learn to lather.
Here is an article that will teach you how to use shaving soap if that is of interest to you.
Conclusion
Back to answering the question about the best shaving cream for safety razor. It honestly doesn't matter what you use. Keep using whatever you always have or switch it up and try shaving with shaving soap for the ultimate shaving experience.