I keep aiming for Clarkesworld (Submission Guidelines:
http://clarkesworldmagazine.com/submissions.html). I seriously enjoy a majority of the stories published by them, enough that I recently ordered the Realms collection just so I can have shiny happy print copies of all of the stories to read wheresoever and whensoever I please. It doesn't hurt that the market also pays $0.10/word and gives out personalized rejections every time. In fact, I have been able to somewhat gauge my writing progress by the advancement of my Clarkesworld rejections.
If you don't like hearing why somebody rejected your story, though, don't submit here. Nick Mamatas is not known for holding back on his opinion. Just remember that it is only an opinion, and you can take it or leave it as you please (I find myself agreeing more often than not, personally).
-Michelle