Dresden Files - wasn't given a fair shake with a shortened season on SyFy (or SciFi then), but brilliant, and really excellently written, acted, and effects, though shoestring, were not bad. I rewatch every year or so.
Watch Helix Online - Free at Hulu - At the end of the 1st (only?) season about now, and I've been relishing every dark secret and hair-raising moment and elevator muzak break that just makes me laugh. Excellence in casting, you don't even notice there's next to no budget - it performs flawlessly without it, and the writing is rock solid. I can't wait to see how they resolve this season and am PRAYING for another season.
Dominion from SyFy channel is about the wars of Angels versus humanity. Very unique perspective on the Bible related mythology that is well shot and interesting characters. While the humanity is confined to few protected cities but one angel, Gabriel, fights for humanity. Creative storyline and twist and turn made this enjoyable to watch. I hope they do more episodes.