If you mean blogs that just review/discuss individual issues/story arcs, I can't think of any off the top of my head that are still up and running. Generally, though, I prefer comics blogs that are more open-ended, meaning not just posting reviews but also discussions of specific creators, characters and other comics-related stuff, as well as non-comics related pop culture topics. In that regard, my favorite comics blog was the now sadly defunct Bronze Age Babies - it's all still up, though, so you can browse the archives. What I especially loved was that there was a lively community of commenters there (I was one of them - I also contributed a few guest posts). Doug, one of the two hosts of Bronze Age Babies, also ran a spin-off blog called Black & White & Bronze, which was dedicated to b&w comics, with, obviously, a focus on the 1970s and '80s. And two of the regular BAB contributors ran a similar follow-up site called Back in the Bronze Age. Both have also closed shop, but again, all of the posts are still up.
Other than that, a few others I can think of that are still being updated regularly (although I have to admit I visit them much more rarely than I used to), include Rip Jagger's Dojo, Steve Does Comics (which has a more UK-centered perspective) and the Peerless Power of Comics. (It's also worth looking at their links to other related or favorite sites, esp. Rip Jagger's - he has a really extensive list.)

Also, since you mentioned essays/articles, you might want to check out The Middles Spaces. It's kind of a general pop culture site/blog, but it's owner, Osvaldo Oyola (otherwise a university professor) is a big comics fan. There are quite a few articles there dedicated to comics, but he and other contributors take a very critical approach, often examining issues like racism and sexism, and sometimes there are considerations of the different ways in which stories can be perceived by people with different backgrounds (i.e., how something lands if you're not, say, white, or male, or straight, etc.).