I write short fiction and I like to get published which means I submit to a ton of markets...often. Everyone knows the top tier markets like Clarksworld or Tor but there are so many smaller markets, some of which are great to deal with, some less so. Here are my favorites in to particular order: 
For constructive personal feedback, nobody beats Shimmer. You'll 
probably only get a sentence or two, and it will probably be terse, but 
how wonderful is it to get editor insight? Fantastic.
DailyScienceFiction
 is my unicorn. I've submitted every single short story I've ever 
written and I've yet to lure this mythical beast into my service. Two 
stories shortlisted but to no avail. And several of my stories have been
 PERFECT for DSF. It drives
 me nuts. I have a running list of lifetime writing goals (maybe I'll 
share it sometime) and landing on DSF is near the top. Someday...
Here's a fun one: Ruthless Peoples Magazine. They are serious when 
they say they want ruthless stories about ruthless people. They are also
 seriously nice. Best rejection letters ever.
In the "Paid More Than I Expected" category, check out Eldritch Press and  Liquid Imagination. For semi-pro markets they treat their authors right.
For themed issues, keep an eye on Penumbra (also good for 
personalized rejection letters) and Crossed Genres. They both come up 
with some great monthly themes and both pay professional rates.
MUST ACT NOW: If you haven't seen this one yet, go check out The Lane of Unusual Traders, a super cool author and reader interactive world. They have a 
great prompt up right now but stories are due the end of August so hurry up! (I 
have 2 in the works)
I've only sent one story their way (still pending) but I love the 
concept behind Scigentasy. We need more gender diversity in speculative fiction 
and that's what they're all about.
Other cool markets that respond with personalized rejection letters:
Untied Shoelaces of the Mind
Pseudopod
Lightspeed (currently closed to submissions)
Fantasy and Science Fiction (great feedback but snail mail only)
Waylines
Stupifying Stories
Kasma SF
Phobos
Finally, one to watch out for. I won't get into why but if I were you I'd avoid TheWiFiles. Not to be trusted.
Other cool markets that respond with personalized rejection letters:
Untied Shoelaces of the Mind
Pseudopod
Lightspeed (currently closed to submissions)
Fantasy and Science Fiction (great feedback but snail mail only)
Waylines
Stupifying Stories
Kasma SF
Phobos
Finally, one to watch out for. I won't get into why but if I were you I'd avoid TheWiFiles. Not to be trusted.
What about you? Any favorites? Any you disagree with?

 
 




