I watched both, and in my personal opinion, show is WAY BETTER.
MOVIE: -Seemed kinda unfinished, cast didn’t really live up to the roles, and it was just a bunch of stuff from the book stuffed into one tiny movie. Casting could be done better. I would never believe for Jace to be the protector, he looked so thin and fragile. Besides his personality and hair, nothing else like Jace. Alec looked too old and was too grumpy, Isabelle was average and Simon was pretty annoying to watch. The whole institute looked aweful. Didn’t like it at all.
TV SHOW: -Way better storyline (even though they didn’t follow the books completely). Casting is kinda perfect. Dom Sherwood did an excellent job as Jace, way better than Jamie Cambpell (not that he sucks, Dom just did it better). Perfect casting in complete. Alec, Isabelle and Simon- perfect casting as well. Scenery is amazing, really well done.