To me, mulberry is the easiest, just prune it, no other maintenance required.
Strawberry is the hardest, I've given up. They tend to die during my hot dry summer and it's just too much work to keep the grass out.
Blueberry takes some work, they are shallow rooted so they need a lot of watering in dry weather. Keeping the grass and such out takes some work but it's manageable. They require high acidity so I need to keep adding sulfur to keep the pH down.
Blackberries aren't that hard, I don't bother trying to keep the grass out that much. I sometimes need to water them during my dry spells to get decent production the following year. Mine have thorns but they do have thornless varieties.
That's the only berries I grow. Are you far enough north for gooseberries?