from what I know, Meohr is not very text-based but more academic. Academic can be subjective. Talk to alumnae from ur high school and find out how hard it is based on that and based on what friends and teachers tell you. I think I heard Seminar has 2 tracks, though not sure how hard the honors track is(i have heard that people say Seminar is easy but ppl say they really do have work, so not sure abt that). Pninim isnt very hard.
Hatzlacha!