Strange Horizons! And right now they’re having a fundraiser.
Strange Horizons is a professional market that pays its writers well. My experience editing my story Birds with Karen Meisner, one of their editors, was really top-notch. She was fully engaged with piece, and made sure the story shined. And Strange Horizons is widely read, too (how do I know? Among other places, Birds turned up in Chinese, was debated in Sweden and reviewed by Locus Magazine)
As I mentioned, they’re having a fund drive, which means you get to directly support a well-curated list of writers producing excellent work. Also, their fund drive includes a number of prizes — donated works from their writers (including, incidentally, a signed copy of Couch).