For me personally:
1.) History (requires a lot of reading around the subject to get the level of detail required for an A/A*. Ridiculous workload even by a level standards, literally death by paper.)
2.) French (All langauages are hard at a level as you need to be virtually fluent to get an A/A*)
3.) English Literature (Again a lot of reading around the subject required to get an A/A* including critics' opinions, not as bad as the workload in history though or the dedication required in French.)
4.) Government and Politics (Comparatively easy as a levels go, if pay attention to the news you can do well in it, also it's still modular so that lowers it down.)