Both have
- time travel !! (though in 365 it's only really once & trying to figure out what happened as they go because they don't know completely since things are changing constantly while in 9 they know everything that happened and they travel and change time numerous times)
- characters fighting against destiny by trying to prevent things that went wrong in the past from happening (specifically deaths)
- mystery/detective work and a whodunnit-esque storyline
- romance though it's only subtle affection in 365 and heavy/plot-driving in 9
- betrayal by a friend/someone close (though in 365 it's someone new they just met, I'd still call it a friend)

This might seem a bit wack, but bear with me.

Both CT and Healer seamlessly combine many genres (CT is more mystery/rom-com/supernatural with some historical/political while Healer is more action/thriller/mystery/rom-com with a bit of political). I think that's something a lot of dramas fail to do well and possibly by that alone you might be drawn to one or the other. Both have solid storylines and characters, though CT is better in terms of deeper meaning and has a lot of things to analyze in the backgrounds of each scene. The mystery/suspense element in both is pretty strong and hooks you pretty well. The romance in both is wholesome and solid, and great OSTs (especially CT's).

CT is criminally underrated and Healer might be (slightly) overrated (though it's def a bunch of good fun), and despite the two seeming completely different, I think viewers of one will probably like the other. Vibes, maybe? Don't think too much and just watch :)