Most horror movies from the 60s-70s are too campy or too "bland" for me. There are a few exceptions, like the first Exorcist film, but had I not watched the first Exorcist film as a child I probably would not like it as much today -- it seems like films with story lines that were treated with some respect back in those days were usually made with a lot of the kind of suspense that would be considered very slow and flat now. I do like how they didn't always have to spell things out for the audience, though, and how so many of them tried to put double-meanings into their films (especially the 60s). Some films that tried this came off as pretentious, though. The rest? Just too cheap and/or campy.
The 80s produced a lot of my favorite horror films, not because they were just sooooo good, but because they were a lot of fun and didn't take themselves too seriously, especially since so many of them focused on the supernatural without trying to make them too weird, and they really focused on trying to make the characters likeable. The films of the 80s had a lot of spirit and attitude that isn't really duplicated in other decades. The problem with the 80s is... they didn't take themselves too seriously. Got a lot of silly stuff from this decade and you didn't get the most complicated plots. So. There is definitely some campiness to be had here.
Then you get today's horror films which range from very bad to very good and not a whole lot of in between. It just depends on who gets their hands on what script, and this argument can be made for ANY decade. That's never changed.
The problem with horror films now, though, is that they rely a lot more on special effects, sometimes to the point that the directors/producers feel these special effects are more important than plot and good acting or characterizations. There are a LOT of good and freshly unique ideas being released these days (as compared to previous decades that used the same types of stories over and over again, just under a different setting), making this past decade rather eclectic -- the main problem is that many of these ideas aren't executed very well, reminding us that an idea isn't good enough to make a movie good. A common mistake being made in today's movies, for example, is "cheating" by making the characters really stupid or shallow in order to move a plot along rather than actually using a well-written story to do that for them. They're also relying a lot more on shock value these days, and this shock value is becoming increasingly more tasteless (including in the humor). Another problem is that many of these ideas and stories have gotten very complicated, leaving them wide open for some very serious plot holes. These plot holes can be avoided with good writing, but, again, that all depends on which scripts are being purchased and who is producing/directing them.
All in all, all decades have their really good and really bad horror movies, although trends and problems with horror films is different for each decade. I have my personal preferences, of course, but that doesn't make any one decade the worse of the bunch. They all have their strengths and weaknesses.