Try your luck with Ringer, Justified, Being Human (the US version, not the UK version), Lost Girl and Game of Thrones (that's a little mature but REALLY good). Breakout Kings is also good for mystery and a little romance, now that it's in the second season, but it's a procedural.
But seriously, I'm a Supernatural fan and I will tell you right now to AVOID it. At all costs. Or watch it, but stop after season three. And never ever watch Sherlock.
Twin Peaks is great for mystery/romance/drama, since you seem to be fond of that! It's only two seasons long and the first season is eight episodes. It's also been a huge influence on most of today's crime and supernatural dramas. It's on netflix as well.