Update, January 2017: Just an update that I'm only on semi-active status these days. I occasionally keep active with mycological and other natural history articles, and the occasional minor edit to an article I happen to be reading. However, I just don't have the time for this project that I once did.
One thing I really appreciate about Wikipedia is the sheer depth of subjects covered, as well as its timeliness. If you wanted to find the obscure details of the present taxonomic status of the Tricholomataceae, an overview of San Francisco's Mission School art movement, the iodine value of lard, a biography of Matokie Slaughter, or just what goes on in the San Francisco Armory, you'll find it in Wikipedia and not the Encyclopedia Britannica. (That's the ideal, anyway, there are still many important topics that are barely covered in Wikipedia. And, of course, there are lots of downsides to Wikipedia – much of the content is incomplete, poorly written, or biased, and most articles lack any proper citation.)
Because I appreciate this depth, my general Wikipedia orientation is "inclusionist". I take issue with the idea that only the kinds of subjects that would go into Encyclopedia Britannica should be included in Wikipedia. However, I'm definitely a moderate inclusionist. I don't buy the argument that Wikipedia should be about "everything". I respect the fact that Wikipedia has standards of notability and that Wikipedia is an encyclopedia and not any number of other things. Because of this, I find myself arguing "Delete" as often as "Keep" in AfD debates. (I've even nominated a few articles for deletion.)
I'm also a bit of a "mergist", in that I'd rather see a single good article with broad coverage about a group of things then a bunch of content forks and ton of tiny little stubs about related topics. To that end, when I start articles on groups of living organisms that aren't well covered on Wikipedia, I typically cover the topic from the "top down", starting with an article on a genus or family and later breaking out articles on notable species as necessary. I find this creates fewer messy content forks.