Beyond the properties of the knife itself and your propensity to properly prepare skin & follicles for severing, there's be nothing more crucial to your post-shave comfort than the quality of the lather. It is a severe understatement to say you're spoiled for choice in the snobby shaving world when it comes to your lather fuel, here being but a pittance of the great stuff that's out there.
As it comes up all the time via emails and telephone calls, I'll go ahead and throw forth some obnoxious dogma wrestling here...remembering, of course, that these are just one man's opinions, and also that because these opinions are mine and not yours, they are correct and you and any other detractors are simply wrong :-)
I tend to evaluate lather fuels by 'ordinal' scoring in individual attributes; that is to say, not by giving some number to each, but by saying "A, B, & C are the same in ___, but D is a magnitude better". In order of importance, here are criteria;
To be sure, speaking chemically shaving cream is just soap - with more water. Speaking practically, creams as a family give you easier lathering creation, more volume, and usually better cushioning, in exchange for you knowingly buying some water in your soap-100 grams of waterless soap's bound to give you more shaves than the same with water.
Shaving 'soap' is as a family more difficult to lather, and their lather is usually more transient and less cushioned. But they're also often better at imparting hydration back to the skin, and the best soaps are, unequivocally to me, far superior in providing slickness than any creams.
Were weighing all the various attributes evenly a possibility for my mind, Sampsons All Natural gets an easy win as 'Best in Show' here. Nearly as easy to lather as a Trumpers' cream, with hydration and slickness in the 2nd-tier class to Zartgefühl and Osma, respectively. Given how both the Osma and Zartgefühl are elevated degree of difficulty items and Sampsons is easy as pie, to have a 2nd-best skill with no fuss makes a top all-rounder. If only it could be as smellertaining as any of the Trumpers...
Best slickness on our board; Osma's hard soap, Dovo & Sampsons right at its heels. Osma's very difficult to lather, transient, with poor cushion and poor volume! At its best, though, absurdly slick. Doesn't smell all that great (we'd once had a walk-in customer say they couldn't even bring themselves to try it twice for the odor, which while an extreme reaction is nonetheless a reaction I'd not be able to conceive of occurring with, for example, Trumpers' lime or "GFT" creams), and in a crowded b-room full of lather fuel I don't even use Osma massively (can be said of all of 'em). But Osma's turn to bat always reestablishes that damn slickness which simply cannot be denied, like a new spin of an old record you forget about. Being slippery's a great asset.
Zartgefühl's "Ziegen Bart" is peerless for hydration among all lather fuel I've used; so extraordinary in this one regard that it took upon a "all known prior, plus one magnitude" position in the mind. It is reasonably slick, but horrible for lather fussiness/staying. I don't mind its faint soapy/citrus/sandalwood aroma-kind of like it, actually-but it is more neutral soapy than catalyst to purchasing. Unremarkable volume. I can get excellent cushion from it upon lucky best efforts, so it has that capacity.
Best smelling fuel for me's Trumper 'GFT', but all Trumper creams tie for top marks in ease of creation and staying power of the lather. Trumper knows a thing or two about fragrance, and whomever they've contracted to make the base for their creams came up with a formula that's simple and voluminous, though neither especially moisturizing nor slick. All Trumper scents are pleasing here. In the same range of smelling excellence, with a cream base superior in hydration, lies Mühle Sea Buckthorn stuff.
I'll vote Proraso "green" in tub as most cushioning, and if not most voluminous, nothing else comes to mind notably superior.
Can't stand the odor, so I doubt we'll ever offer it (it smells like an old man's body odor!), but if you've never used Tabac, you really should try it, as that's a terrific all-around soap (minus the odor...let's not forget that part). Mitchell's Wool Fat is pretty much universally respected, too, but its lanolin - like upon Musgo Real, another esteemed item with heavy lanolin influence - causes me to tingle and burn so badly that I cannot give either a second chance...but were my friend calling from across the country in shaving shop with money to burn in his pocket, Tabac and Mitchell's Wool Fat and Musgo Real would earn a begrudging vote as must-try items; lots of folks take to lanolin just fine, after all. Lastly, there is the French Martin de Candre; it is terrific, sublime stuff, and if you like it, you're pretty sure to like Sampsons' All-Natural, for their formuations are very similar indeed.
We must collect sales tax if shipped within Florida.