I never said Brazil was a perfect movie, but sentimentalism isn't its biggest problem. I haven't seen To Kill a Mockingbird since I was in high school. That's simplified kiddie crap so I wouldn't be surprised if it is overly sentimental.
V, I'm not quite sure what you are getting at. It has a fair bit of telling instead of showing (comic book roots shining through), but the only really clear incident of sentimentalism was the note Evey finds about the lesbian, and there's kind of a twist on that since we don't know whether the note is real. It does have an emotionally manipulative effect on Evey, though.
Either way, Brazil and V may have some sentimentalism in them, but they are not driven by it like Gump and M$B.