Ideally I'd get two millstones, which grind finely, perfectly, and with zero labor--hence villages being built around them for thousands of years. Unfortunately for me, I don't have access to a watermill or windmill at my apartment, so I need to regress to cavemen's tools for my occasional crushing and grinding. Pestles are the hand tools and mortars are the receptacles; every civilization has their own.
Paleolithic cavemen used holes in cave floors. Neolithic cavemen invented portable holes. Biblical Jews shared millstones in a village. Frenchmen use Peugeot handmills because fuck your village. Greeks use olivewood for aioli or whatever. Italians use marble for pesto because "it emulsifies better" (read: it's a delicate display piece). Japs use suribachi to grind moldy rice into miso. Weebs use suribachi to collect dust in their cabinets. Indians use electric blade grinders because they're grinding dried spices. Mexicans use molcajetes to grind avocados into guacamole. And so on.
My ideal mortar would be as large as I can carry and would come with both straight and mushroom pestles. A straight pestle seems best for crushing and a mushroom pestle seems best for grinding. Amazon does not sell this ideal set.
America's Test Kitchen used to recommend the Cilio Granite David mortar and pestle, but I haven't been able to find it for sale. Their criteria (which have since been paywalled as far as I can tell) boiled down to the mortar being huge and the pestle being heavy, and applying these criteria to what I see when browsing aisles makes every retail mortar and pestle look like junk.
So I've been using my blade grinder and food processor for some mortar and pestle jobs like pesto and non-pepper spice grinding. I'd like to get something that fulfills my caveman desire to smash things.