There's lots of valid critiques of HPMOR (I recently reread it and the early chapters are painfully obnoxious), but I think "no meaningful plot" and "doesn't do anything interesting" are objectively false. It has like a dozen interacting plotlines, and is massively different from any other HP fanfic and most media in general. It is popular for a reason. If you dropped it early, I'd encourage you to try again.