Best and worst is always totally subjective. Heck, sometimes it just depends on your mood when you watch it. I can remember laughing hysterically watching There's Something About Mary and those are not typically the kind of gags and jokes that would normally make me laugh. Conversely, I remember watching Napolean Dynamite with a group of people, all various ages, and they were all laughing but I didn't even laugh once. It just didn't strike me as funny.
As far as Blair Witch goes, I thought it exceedingly over hyped and over rated. I thought it was boring. I get what they were trying to do and I actually think it's a good idea, leave more to the imagination as opposed to slash and gore, but it just didn't do it for me. On the hand I though Paranormal Activity did a pretty good job at setting that tone. Director's cut ending being the best one, although the theatrical release ending works for the sequel.
Some of the old movies from the 40s, 50s and 60s I can remember watching when I was a kid, especially the old monster movies they used to show on television. Watching them as a adult they are not so entertaining but I still have a somewhat nostalgic love for some them.