I haven’t tried them all, but I have tried many of the top artisan soap bases over the years. Currently, I’m really loving Declaration Groomings milksteak base. What is your current favorite?
Thus far the easiest and most luxurious lather I've gotten is from PAA's CK6 base. I shaved with Cane last night: hadn't taken it out in months. Very easy to bowl lather and raise a consistency much like marshmallow fluff. A little goes quite a distance. The shave was very comfortable. The aroma...not quite my thing but not terrible.
I recently added a couple of Mike's Naturals and like it as well, though it is not as easy to lather. I'm close to dialing this in. What I've discovered is letting the soap hydrate in a small amount of hot water first, then using a barely damp brush to start off, hydrating judiciously as you go, has been producing better results overall.
I really enjoy all the artisan soap bases. #1 for me would be Barrister and Mann’s Omnibus base. It just keeps taking water, even after you think it can’t hold any more.
Others I like for various personal reasons: Stirling (easy to lather), Declaration Grooming (great post shave feel), Noble Otter, MacDuffs, Southern Witchcrafts, Chiseled Face, Spearhead Seaforth Highland base, House of Mammoth.
I haven’t tried a ton of different bases, but Stirling’s Mutton Tallow and SV 4.3 have been the best ones so far. Having said that, Stirling’s beef tallow is an excellent base as well.