easy: any class that has one sole reason in a grp... like light tanks (charge3, new purge, banelord etc), dmg-dealer casters like chanter, bainshee, wizard, sm etc, they are there to make dmg with close to zero util, so need to concentrate on a few things only
hard: any healer class nowdays, mainly the ones with 3 useful lines (heal-shear-rebuff- root/demezz/cc), utility casters like light eldritch - tri spec caba - sorc too (most of em are like, mezz and Lajftap*100000)
Tho easy or hard is not the right word here, maybe complicated or less complicated would be better, couse for any char in camelot you need like:
1, a good grp
2, reflexes - decision "build"
3, patiance

4, experience