Of those listed, I only watched a full season of Arrow and Once Upon a Time. I like Arrow well enough. I continue to watch on Netflix. I thought Once Upon a Time was terrible.
I haven’t watched any of the shows in the OP. But I watched several episodes of Forever and it was a decent series. I’m surprised it didn’t get renewed.
I really like Grimm.
I like Arrow, too, but not as much. I also like Flash. (And looking forward to Supergirl - all from the same creators).
I really liked Sleepy Hollow’s first season, but kinda forced myself through the second season. Hope it gets better for the third.
My wife really likes Once Upon A Time. I can take it or leave it.
I will +1 jsgoddess and suggest Supernatural. Very much like Grimm, but way more seasons. A very involved mythology and still lots of fun.
Flash is great, but the main “will-they-won’t-they” romance is incredibly cringe-worthy. Watch it, but you might want to fast forward through pretty much any scene that has just Barry and Iris in it.
I have enjoyed watching Grimm from the beginning. I liked Haven for a few seasons, but my interest started to flag, and when they killed off one of my favorite characters, that kind of sealed it for me. Sleepy Hollow had a fantastic first season followed by a pretty spotty second one, but I really feel like that show has a chance to bounce back, between the terrific chemistry of the two leads and the fact that certain characters that weren’t really working appear to have been taken out of the mix. And Warehouse 13 is a fun little show that I wouldn’t have minded if it had lasted a season or two longer. One of the better characters isn’t in the pilot, so you might want to wait for her to show up before you make your final decision about it.
Warehouse 13 & it’s sibling show Eureka are things that you watch when you have laundry to fold. They’re consistently ok shows. Though you didn’t ask about it, I’d put The Librarians in the same category
I didn’t like Haven at all.
Sleepy Hollow is just nuts, but in a good way. The series knows that it’s a ridiculous premise and that it has insane plotlines and fully commits to it. As you like Supernatural, you may like this as well.
I’m going to partially/reservedly suggest Continuum. It’s sci-fi more than fantasy. (Time traveler from a heading-toward-dystopian future shows up in the present). It’s almost close to being a good show. The writers keep almost asking interesting questions and then side stepping exploring an answer by sending someone down an alternate timeline or blowing up a building or something.