The treatment of Harrison Wells is the most interesting character arc on The Flash. Tom Cavanagh deserves a lot of the credit for making the two iterations of Wells (/Eobard Thawne) distinctly separate characters but both recognizably similar and equally compelling. You never quite know whose side this guy is going to be on.
You gotta love Cisco. At first just the comic relief of the show who filled in the perfunctory role of naming the weekly villains, Cisco has become The Flash’s breakout character – he’s basically a superhero in his own right now as Vibe. Kudos to Carlos Valdes for nailing it in his first on-screen acting role.
Who else could be top of the list, though, but the Fasted Man Alive? While a big part of the show’s success is its loveable ensemble, the glue that holds it all together is Grant Gustin as Barry Allen. Always trying to do the right thing no matter what, Barry is a true hero – and probably the most endearing superhero on TV right now.