Warehouse 13 - An endearing sci-fi show about a warehouse full of weird artifacts. Despite some intense episodes, it offered mainly a light, feel-good entertainment, and featured a really well-crafted send-off.
Fringe - Starts out weird, then it goes totally off the rails, but in a good way. Also wrapped up nicely.
Two shows that weren’t mentioned yet:
In a similar vein to Warehouse 13, Eureka is also a very fun SyFy channel show.
And the two shows are connected in the same universe!
Oh yeah! I’d actually forgotten that.
Fringe: starts weird, but then they introduce the multiverse.
Honestly great, they knew how to change things up when the “strange phenomena of the week” formula was about to get old.