Maror is prepared fresh at home rather than preserved or bought ready made, freshly grated horseradish root or whole romaine lettuce leaves being the two most common choices, and which one a family uses tends to track regional history more than personal taste.
A regional split driven by climate
Ashkenazi communities in colder parts of Europe favored horseradish, a root that keeps and remains available through the season around Passover, while Sephardi and Mizrahi communities in warmer regions more often use romaine lettuce, chicory or endive, greens that were simply easier to source fresh where they lived. Neither choice is more correct than the other, the requirement is bitterness, not a specific plant, and communities settled on whatever bitter vegetable their climate supplied reliably.
Preparation and the measured obligation
Whoever is cooking for the seder grates or prepares the maror, no ordination or special training is required, and the obligation to eat it is measured rather than symbolic, a minimum quantity roughly the size of an olive, a kezayit, is specified for the act to count as fulfilling the commandment, a genuinely technical detail that shapes how much a household actually prepares.