Using imitation crab or lump crab meat is a matter of preference and of budget. Imitation crab, especially when it's on sale, is a lot more affordable than lump crab meat. Imitation crab and lump crab meat do taste different, but in a recipe like this, where you do taste the crab flavor but there are other strong ingredients (namely, the cream cheese), imitation crab works really well. I wouldn't suggest using imitation crab in something like a crab cake. But if you're making that on a budget, I would say make Tuna Cakes instead.